Cobalt recovery from the stripping solution of spent lithium-ion battery by a three-dimensional microbial fuel cell

Abstract

Cobalt (Co) recycling from the spent LIBs not only favors the ecological protection also meets the supply chain of Co in the international market. In this research, a three-dimensional microbial-fuel-cell (3D-MFC) two-chamber system with granular activated carbon (GAC) microelectrodes was constructed to remove and recover Co from the stripping cobalt sulfate solution. The 3D bio-electrochemical (BE) system exhibited the largest voltage output and power production at 12th day during the acclimation, achieving the maximum power densities (W/m3) of 6.24, 10.29, 14.52, 12.59, and 8.78, respectively. The GAC prepared at 500 °C achieved highest removal and recovery efficiencies of Co in the 3D-MFC system. The maximum removal efficiency of 98.47%, the recovery efficiency of 96.35%, the power density of 11.34 W/m3, and the columbic efficiency of 28.74% were obtained in the orthogonal experiments. The influence of the operating time on the removal and recovery of Co was more obvious than the electro-output of the system. The addition of ammonium carbonate to the 3D-MFC systems clearly increased the precipitation of Co. The stacking of GAC particles in MFC had strengthened the adsorption of Co ions by intensifying the acidic-alkaline pathways during the 3D BE process. The removal and recovery of Co ions from the stripping solution in the 3D-MFC experiments were mainly achieved by the electromigration, electrostatic adsorption of GAC, and chemical precipitations of cobalt hydroxide and cobalt carbonate. A continuous process was suggested for the 3D-MFC application integrating to the traditional recovery procedure of Co from the spent LIBs at the pilot scale.