For the development of the collection of gold from electronic waste using bipolar electrolysis: observation of carbon electrode surface with topografiner

Abstract Aqua regia has been primarily used to salvage gold from electronic waste. We previously developed a gold dissolution method using salt water instead of aqua regia by applying bipolar AC electrolysis as a safer and more environmentally friendly gold recovery method. However, one of the problems with this recovery method was the deposition of gold on the electrode surface during AC electrolysis. In this paper, we have used a scanning tunneling microscope but set the bias voltage to more than 10 V; scanning the probe under the same condition as the topografiner, which was developed before the invention of the scanning tunneling microscope. By increasing the distance between the scanning tip and the sample surface, we have made it possible to observe the rough sample of gold clusters deposited on the carbon electrode surface.