Superhydrophobic Self-Cleaning Composite of a Metal–Organic Framework with Polypropylene Fabric for Efficient Removal of Oils from Oil–Water Mixtures and Emulsions

Here, we report a metal–organic framework (MOF) [Hf6O4(OH)4(TFNDC)6]·6H2O·2DMF [SHMOF, where TFNDC = 1-(2,2,2-trifluoroacetamido)naphthalene-3,7-dicarboxylate], which possesses excellent chemical and thermal stability along with remarkable hydrophobic characteristics. The hydrophobic SHMOF was used for in situ coating on the polypropylene (PP) fabric to make a superhydrophobic SHMOF–PP fabric composite. The immobilization of nanocrystalline particles of SHMOF creates a nanoscale hierarchy that enhances the hydrophobicity of the material. The superhydrophobic SHMOF–PP composite showed a water contact angle of 160°. The successful integration of the MOF compound with PP fabric was confirmed using field-emission scanning electron microscopy, X-ray powder diffraction spectroscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray analysis experiments. Superhydrophobic SHMOF–PP composite displayed a high separation efficiency (93–99%) for separating light, heavy, and crude oils from oil–water mixtures. The flux for oil–water separation was found to be 13–18k L m–2 h–1. Importantly, the SHMOF–PP composite can be used repetitively up to a minimum of 20 times for oil–water separation. The recyclability was also maintained in high acidic and alkaline media. Moreover, superhydrophobic SHMOF–PP composite showed excellent oil absorption capacity (29–39 g/g) for heavy and light oils at ambient temperature. A gravity-driven active-filtration process and separation against the gravity process were also performed to examine the flexibility of the composite for separation. We demonstrate that the SHMOF–PP composite has the merit of very high separation efficiency, absorption capacity, good recyclability, and exceptional robustness, showing high potential for versatile oil–water separation. Additionally, the material displayed noticeable self-cleaning and antifouling properties. The SHMOF–PP composite also exhibited good efficiency (95–99%) and flux density (1845–1899 L m–2 h–1) for the separation of water-in-oil emulsions.