High-efficiency separation performance of oil-water emulsions of polyacrylonitrile nanofibrous membrane decorated with metal-organic frameworks

A nanofibrous polyacrylonitrile membrane decorated with metal-organic frameworks (MOFs) of UiO-66-NH₂ is prepared via a simple and flexible self-assemble method. It is found that the membrane shows high-efficiency separation performance of oil-water emulsions, due to the hydrophilic carboxyl and amino groups of UiO-66-NH₂ and the gaps between neighboring UiO-66-NH₂. Remarkably, solely driven by gravity (∼0.01 bar), the obtained membrane can effectively separate oil-water emulsions with an excellent separation efficiency (>99%, TOC < 10 mg/L) and a high flux (2107 Lm⁻² h⁻¹). It is demonstrated that the hydrophilic carboxyl and amino groups of UiO-66-NH₂ enhance the superhydrophilicity and underwater superoleophobicity of the membrane so as to greatly improve the antifouling properties of the membrane. Besides, because the size of gaps between neighboring UiO-66-NH₂ is mostly much smaller than that of oil drops and the UiO-66-NH₂ are underwater oleophobic, the oil drops hardly enter the gaps between neighboring UiO-66-NH₂ so that the gaps provide much more water flow tunnels, which obviously enhance the flux of the membrane. In this study, we present a new avenue of building MOFs loaded nanofibrous membrane with excellent oil-water separation performance.