Sustainable electrochemical gold dissolution process based on triboelectric nanogenerator

Abstract

The development of sustainable, energy-free dissolution methods is crucial for gold recycling. For the first time, we have achieved the dissolution of gold through a triboelectric nanogenerator (TENG). With 1 wt% Au/SiO2 as the research subject in KI solution, the gold dissolution efficiency can reach 100 % in three hours driven by R-TENG. However, by using a direct current (DC) source with 25 mA and 5 V, the gold dissolution efficiency is only 85 % after the same operation time. Meanwhile, to achieve the same 85 % gold dissolution rate, the total charge consumed from TENG is only 1.6 % of that from the DC source, indicating an ultrahigh charge utilization rate. Thus, the side reactions such as water splitting and the formation of the iodine oxide film in KI aqueous solution can be avoided by using TENG, which blocks the adhesion on the anode and facilitates the reaction. The amount of gold extracted from the waste central processing units (CPU) board (4 × 4 cm) by the solution method could reach 6 mg/piece. Hence, TENGs provide a new direction for the recovery of other metals in secondary resources and many other applications in the direction of electrochemistry can be also inspired.