One-step recovery of precious metal ions from oil/water emulsions by multifunctional CNTs-PAH/MXene membrane for further recycling utilization

The complex composition of actual industrial wastewater requires membrane separation technologies that can treat multiple contaminants simultaneously. However, currently designed multifunctional separation membranes do not combine the recovery of the rare resource of precious metal ions. In this paper, the carbon nanotubes grafted with polyacrylhydrazide (CNTs-PAH) and Ti 3 C 2 T x MXene nanosheets were synergistically constructed as CNTs-PAH/MXene membranes. The membrane is initially capable of efficiently separating five kinds of water-in-oil (W/O) emulsions, and the separation efficiencies are all higher than 96 %. Moreover, the membrane can accurately and selectively recover precious metal ions from C/W emulsions, with maximum absorption capacities of 527 mg g −1 , 631 mg g −1 and 464 mg g −1 for Ag, Au and Pd, respectively. The post-recovery membrane precious metal ions can be further used to catalyze methylene blue and p-nitrophenol with catalytic efficiency above 95 %. The composite membrane has good structural stability and efficiency retention during cyclic separation. In addition, the regenerated silver nanoparticle composite membranes showed an inhibition rate of 88.97 ± 0.37 % against Staphylococcus aureus. This work introduces a fresh strategy to construct a long-lasting multifunctional separation membranes with simultaneous precious metal ion recovery.