Selective Pt recovery from spent catalyst enabled by hierarchical porous poly(imine dioxime)/polyethylenimine composite membrane for recycled Pt/C catalyst

The ever-increasing supply to demand contradiction and nonrenewable characteristics of platinum (Pt) have urged the extensive research enthusiasm for its efficient recovery from electronic waste and inactivated catalysts. Herein, an ultrathin, highly cross-linked hierarchical porous poly(imine dioxime) (PIDO)/polyethylenimine (PEI) (denoted as PIDO/PEI) composite membrane has successfully fabricated for highly effective and selective recovery of Pt from acidic aqueous media. As expected, the resulting PIDO/PEI membrane demonstrates outstanding Pt recovery performance via the sorption/reduction mechanism, including ultrahigh uptake capacity (4185 mg g−1), rapid kinetics, superior selectivity, and excellent regeneration capability. Significantly, 99% of Pt recovery efficiency is achieved from the leachate of spent Pt/C catalyst, highlighting its feasibility of the proposed PIDO/PEI membrane in the complicated system. Furthermore, Pt-loaded PIDO/PEI membrane can be effectively converted to the recycled Pt/C (18.3 wt% Pt) catalyst with enhanced electrochemical surface area (ECSA) over the commercial Pt/C (20 wt% Pt) catalyst. This work will provide a viable blueprint for the recovery of precious metals from spent industrial catalysts.