Recovering platinum from wastewater by charring biofilm of microbial fuel cells (MFCs)

Reduction in and recovery of precious metals are research hotspots in the environmental engineering field. In this study, we investigated the transformation and distribution of platinum in microbial fuel cells (MFCs) and demonstrated a feasible approach to recover platinum (Pt) from wastewater with less than 16.88 mg/L platinum through charring biofilms in MFCs and generate Pt/C catalyst. The optimal reaction condition was identified, and charred biofilms were analyzed via SEM-EDS, XRD and XPS. Results showed that less than 10% of Pt was in MFC effluents, and less than 0.5% was in the cathode chamber when the influent concentration was below 16.88 mg/L. Close to 40% of Pt could be recovered. The recovery efficiency could be higher should the reactions run longer. SEM-EDS and XRD results indicated that the metallic form Pt0 is one of the reduction products in MFCs. XPS results induced that Pt (IV) was reduced to Pt (II) and Pt0. Keywords: Microbial fuel cells, Platinum, Bio-reduction, Recovery, Sludge