MXene/NH2-MIL-125 composite membrane for efficient oil/water separation, noble metal recovery, and photocatalytic purification of complex wastewater

A “separation-recovery-purification” strategy inspired by glass sponges is proposed. • The composite membrane achieves an oil/water separation efficiency of over 97.7%. • The composite membrane attains over 97% recovery efficiency for noble metal ions. • Recycled membranes gain over 97% degradation efficiency for dyes and antibiotics. • The recycled membranes display excellent antibacterial capacity. Existing MXene-based composite materials face significant challenges in combining water purification with precious metal recovery. For complex wastewater systems containing oil–water emulsions, precious metal ions, and organic dyes, there is an urgent need to develop efficient and multifunctional MXene-based composite membranes to enhance their applicability in complex aquatic environments. In this study, MXene nanosheets and NH 2 -MIL-125 were assembled into MXene/NH 2 -MIL-125 composite membranes via vacuum-assisted filtration. The optimized composite membranes exhibited excellent hydrophilicity and underwater superoleophobicity, achieving oil–water separation efficiencies exceeding 97.7% in various emulsion systems. In addition, the membranes enabled the selective recovery of Ag + , Pd 2+ , and Au 3+ ions, with recovery efficiencies above 97% for all three ions and maximum adsorption capacities of 887.86, 845.46, and 806.57 mg·g −1 , respectively. After metal recovery, the resulting M-3@Ag membrane exhibited markedly enhanced photocatalytic performance and excellent antibacterial activity. During cyclic purification tests, the composite membrane successfully implemented an integrated “separation–recovery–purification” strategy. Overall, this work provides a green and efficient approach for the treatment of complex wastewater and the sustainable recovery of precious metal resources, showing great potential for practical applications.