Preparation of Floating Au/PVP Film on Water for a Green and Rapid Extraction of Gold Ion

Currently, the demand for gold is ever increasing while the reserve of gold ore is very limited. The extraction of gold ion from various waste effluents is now a very important way for a sustainable gold supply. In this work, a green, selective, simple, easy, cheap and energy efficient way to recover Au ion from a mimic waste stream containing Au, Zn, Fe and Cu ions has been developed using a room temperature electron reduction with argon glow discharge as the electron source. Metal ions with sufficiently high standard electrode potentials can be reduced by such electron reduction. A selective reduction of gold ion has been thereby established, where other metal ions remain in the solution. With the addition of poly(vinylpyrrolidone) (PVP), an Au/PVP floating film is rapidly formed on the surface of water within a few minutes. This makes the collection of the recovered gold very easy with very high recovery yield. The gold recovery yield reaches 87.19% in 60 s and 99.96% in 480 s under the reaction conditions tested.