The importance of gold recycling from e-waste (electronic waste) is continuously increasing due to raising gold demand and the need for new recycling methods for this complex waste. The low content of gold in e-waste such as WMPPCB (waste mobile phone printed circuit boards) makes the traditional recovery methods (cementation, ion exchange, carbon adsorption, solvent extraction and electrowinning) for the extraction step inefficient and costly. Herein, in this study, for the first time, we report an efficiently and economically strategy for the recovery of low contents of gold from e-waste using Fe-electrocoagulation. WMPPCB aqua regia leachate containing low concentrations (5.15 g/L) of gold was treated by electrocoagulation at pH=6 and a tank voltage of 0.5 V. The results showed that the gold interception rate reached 99.93% and the gold content in the dried electrocoagulation sludge reached 5.9%. The other platinum group metals simulations were also treated by electrocoagulation under the same conditions and their dried sludge contents reached: Pd 13.69%, Rh 7.01%, Ag 4.9% and Pt 2.54% respectively. By XPS and TEM-mapping analysis, Au (III) and other platinum group metal ions in solution were first adsorbed by the iron (oxy)hydroxides generated by electrocoagulation and then reduced to nano-gold. In terms of energy consumption, its economic feasibility has been evaluated. In overview, this work provides a sustainable route for the recovery of gold from e-waste containing low contents of gold.
 

e-waste; gold recovery; electrocoagulation; nano-gold