Morphology modulation of Cu2S nanoparticles for cleaner Au (III) recovery from aqueous media: excellent capacity, illustrious selectivity

Developing an efficient and cleaner technology to recover gold (III) from aqueous media is vital for both economic and environmental perspectives. Herein, Cu2S was first found with well Au (III) recovery ability, rod and flower-like Cu2S nanoparticles prepared by dynamic modulation, with jaggy micro-surface and relatively hard-wearing shape, was found with well Au (III) affinity. Results proved that this adsorbent could work better over a relatively wide pH from 2 to 5, and temperature from 25 to 55 °C, and that attained high gold capacity of 5,582 mg/g which obviously exceeded other reported adsorbents, indicating well application potential. XRD, TEM, and XPS studies demonstrated that adsorbed Au (III) was reduced as Au (0) by Cu2S. DFT studies verified that Au (III) recovery is related with the formation of "Cu-S-Au" bridge-like linkage and the unceasingly produced new adsorption sites after adsorbed Au atom's migration and agglomeration. Au (III) recovery ability and selectivity in the actual sample was proved to be well too. Also, more than 90% gold on Cu2S could be recovered with HNO3. This study is of great theoretical and practical significance for cleaner Au (III) recovery from various aqueous media.