Electroreduction recovery of gold, platinum and palladium and electrooxidation removal of cyanide using a bioelectrochemical system

Electroreduction and electrodeposition recovery of Au, Pt, and Pd was performed in the novel bioelectrochemical system (BES) with carbon electrode. Total voltametric charge of carbon brush reached 0.180 C cm −2 . Lower electrochemical porosity confirmed that the active sites of carbon brush were more present on the surface of electrode, and charge transfer resistance and the resistance of the biofilm of carbon brush was only 5.2 Ω/1.5 Ω. Electroreduction products of metals were confirmed by scanning electron microscope, X-ray photoelectron spectroscopy, and X-ray diffractometer. Calculated energy efficiency of the Au, Pt, and Pd reached 2.22 kWh kg −1 , 4.45 kWh kg −1 and 2.27 kWh kg −1 , the maximum power density 1.16 W m −2 . The engineering application potential of the BES and electrolytic cell was explored for the treatment of cyanide tailings leaching solution, realizing the electroreduction recovery of Au/Pt/Pd and the electrooxidation removal of cyanide by self-generated chlorine simultaneously (CN − removal efficiency 100%). • Self-produced bioelectricity is recovered for the electroreduction of Au/Pt/Pd. • The energy efficiency of Au, Pt, and Pd reaches 2.22 kWh kg −1 , 4.45 kWh kg −1 and 2.27 kWh kg −1 . • Electrodeposited metals dense granular solids are observed on the surface of electrode. • Electroreduction recovery of metals and electrooxidation removal of cyanide were realized.