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Graphical abstract Highlights • The new multifunctional UF membrane with ultrahigh MOF loading of 67% was prepared. • The new membrane showed much better efficiency for MB removal comparatively. • Acceptable ultrafiltration and permeability performance of the new membrane was kept. • The relationship and contribution of adsorption & catalytic oxidation were clarified. • The mechanism of decontamination, ultrafiltration and permeability was proposed. Abstract Multifunctional ultrafiltration membranes need to be further developed with ultrafiltration performance and high multifunctional decontamination efficiency. Here, the MIL-PVDF multifunctional ultrafiltration membrane with ultrahigh MIL loading was demonstrated by a new blending method of predispersion in acetone and thermally induced phase separation. Due to the improved dispersity and restriction of pore size, the MIL-53(Fe) mass loading was as high as approximately 61%. The new membrane showed high performance for methylene blue (MB) removal and maintained high permeability and ultrafiltration efficiency. The characteristics of the membranes were analyzed to explain the above advantages. Meanwhile, compared to the traditional blend ultrafiltration membrane, the 67-MIL-PVDF membrane showed an 9-fold increase in effective treatment volume for more than 75% MB removal. The contribution and efficiency of adsorption and catalytic oxidation were analyzed and explained. The relationship between them was confirmed as being independent, and the reasons for this independence were proposed. Additionally, the mechanism of multifunctional decontamination and permeability by MIL-PVDF membranes was proposed. Moreover, the 67-MIL-PVDF membrane was also suitable for long-term run and real wastewaters treatment. In conclusion, this study sheds new light on the preparation strategy for multifunctional blend ultrafiltration membranes with ultrahigh particles loading displaying high decontamination and permeability performance. [ABSTRACT FROM AUTHOR]

• A novel designed PVA/Cu-iMOFs/PVDF UF membrane is prepared successfully. • Cu-iMOFs particles immobilized on PVDF membrane surface is reinforced by amido bonds. • Membrane exhibits outstanding selectivity and reusability toward ClO 4 − trapping. • Membrane shows excellent permeability and stability in cross-flow filtration. • The mechanism is specific exchange between R-SO 3 group and tetrahedral oxo-anion. We design a novel cationic metal-organic framework hybrid ultrafiltration polyvinylidene fluoride membrane (PVA/Cu-iMOFs/PVDF-0.05) and report its unique capture of aqueous perchlorate (ClO 4 −) at ppm-level. This membrane outperformed traditional adsorption materials and exhibited a specific affinity toward ClO 4 − in the presence of various competing anions at greater levels (up to a concentration ratio of 20). In the batch experiment, the ClO 4 − removal ratio reached 99.6% over a wide pH range (3˜10). Membrane filtration by using a 12.56 cm2 PVA/Cu-iMOFs/PVDF-0.05 membrane could effectively treat 4.71 L of ClO 4 −-contaminated water before breakthrough occurred, while maintaining a satisfactory permeability (˜627.32 L/(m2 h bar)) and antifouling property. The exhausted membrane could easily be regenerated in aminoethanesulfonic acid solution for repeated use with a negligible decrease in capacity. Moreover, the membrane showed excellent long-term stability in a cross-flow filtration process due to the amido bond between the Cu-iMOFs and membrane surface as well as the "protection" of polyvinyl alcohol. Selective and reversible ion-exchange between the sulfonic acid (R-SO 3) ligands of Cu-iMOFs and tetrahedral oxo-anionic species was verified to be the pathway for ClO 4 − trapping. Thus, other problematic elements that also occur in tetrahedral form in water can be removed by this method. [ABSTRACT FROM AUTHOR]