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

Abstract

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.

An eco-friendly approach using a nonfluorous self-cleaning metal–organic framework composite and membrane for oil–water separation

“…To work out an easy and ecologically sound solution, numerous materials have been developed to separate oil–water mixtures employing superhydrophobic and superhydrophilic materials. 1 The superhydrophobic absorbent or membrane materials used for oil–water separation are metal mesh-based membranes, 2 sponge-based composites of fluorinated linkers, 3 fluorinated polymers, and aerogel materials. 4 Metal-based membranes have the drawback of corrosion.…”

Superhydrophobic and Conductive Foams with Antifouling and Oil–Water Separation Properties

“…The results have demonstrated that the separation efficiency of the PDMS-GR-Cu foam was very high, exceeding 99% for the tested oils and organic solvents with high flux rates (6216–11 700 L m –2 h –1 ) that are comparable or higher compared to the other fabricated filters (Figure b and Table S3). Although other oil–water separators exhibit superior separation performance, − they do not provide any mechanism to kill adherent bacteria, which may lead to the loss of their permeate flux, limiting their use in bacteria-contaminated environments . The foams were further examined for reusability and separation efficiency by taking chloroform as a model pollutant since both are characteristics necessary for practical application.…”

Preparation of two kinds of membranes with reverse wettability from waste masks for continuous oil/water separation

“…25 These show great potential for versatile oil–water separation but still have the disadvantages of high cost and low throughput. 26…”

“…25 These show great potential for versatile oil-water separation but still have the disadvantages of high cost and low throughput. 26 In recent years, the COVID-19 pandemic has created environmental challenges induced by the extensive use of face masks as more than 130 billion waste masks are disposed of globally every month. 27,28 Most waste masks are sent to landll or burned at high temperatures but both of these methods have negative environmental impacts.…”