Platinum recovery from ICP wastewater by a combined method of biosorption and incineration

A high performance biosorbent, polyethylenimine (PEI)-modified biomass, was prepared by attaching PEI onto the surface of inactive Escherichia coli biomass. Wastewater containing platinum was collected from an industrial laboratory for inductively coupled plasma (ICP) and used for the recovery study. The maximum platinum uptake of PEI-modified biomass was enhanced up to 108.8 mg/g compared to 21.4 mg/g of the raw biomass. Kinetic experiments revealed that sorption equilibrium could reach within 60 min for the PEI-modified biomass. The results of FTIR and XPS analysis of Pt-unloaded and Pt-loaded PEI-modified biomass indicated that electrostatic interaction was the main binding mechanism between the platinum ions and the binding sites on the surface of the biomass. Metallic form of platinum in ash was recovered by incineration with a recovery efficiency of over 98.7%. Furthermore, XPS, TEM and XRD results confirmed that the platinum recovered were both forms of Pt⁰ and Pt²⁺.