Closed-loop process for selective leaching and recovery of palladium from spent auto-exhaust catalysts using iodotrihalide ionic liquids

The recovery of palladium from spent auto -exhaust catalysts (SAE -catalysts) is of great significance for resource sustainability. Herein, we proposed an efficient closed -loop leaching and recovery method for palladium from SAE -catalysts using iodotrihalide ionic liquids (ILs). Recovery design was explored aimed at green leaching and process simplification. Iodotrihalide ILs exhibited exceptional performance in terms of leaching efficiency (99.1%), selectivity (selectivity > 6.8 x10(3)) and reusability (over 6 cycles). The mechanism study revealed that excellent leaching performance was attributed to the redox and complexation. Additionally, the chemical reaction -controlled model was best suited to describe the leaching process. Notably, under the optimal conditions determined by the response surface methodology, a high -purity Pd(II) solution (purity > 99.8%) was obtained. More significantly, it was ideal for practical applications due to the low -viscosity (36.0 cP), mild (55 C-degrees) and onestep leaching and recovery. In conclusion, this work provides an eco-friendly method for recovering palladium from SAE -catalysts with its non -high corrosiveness and low environmental impact.