h-BN/MIL-53(Al) MOF hybrid-enhanced cellulose acetate butyrate composite membrane for sustainable oil adsorption and oily wastewater separation.

The removal of oil contaminants from water is a great challenge for sustainable wastewater treatment, clean water production, and environmental protection. Electrospun membranes based on cellulose acetate butyrate (CAB) were prepared for oil adsorption and oil/water separation in this study. The performance enhancers were hexagonal boron nitride (h-BN), MIL-53(Al) metal-organic framework (MOF), and h-BN/MIL-53(Al) hybrid prepared by simple ultrasonication-assisted synthesis. The hybrid-containing membrane (CAB/1.5B1M) exhibited the highest oil adsorption capacity of 65.8 ± 2.6 g g-1, which was higher than those of neat CAB and the membranes only containing h-BN or MIL-53(Al). This improvement was attributed to the hybrid h-BN/MIL-53(Al) filler that induced a more open fibrous architecture and higher hydrophobicity, hence enhancing the oil uptake and retention. The adsorption capacity was increased by ~101% relative to the CAB membrane. The CAB/1.5B1M membrane adsorbed different oils on the solid and water surfaces and retained 73.5 ± 1.4% and 77.6 ± 3.1% of the initial adsorption capacities for soybean oil and used motor oil, respectively, after ten cycles. Furthermore, the membrane also enabled an effective gravity-driven separation of oil/water mixtures and water-in-oil emulsions, achieving a separation efficiency of 91.1% for diesel/water mixtures and no water was detected in the separated oil. The membrane could also wrap a hydrophilic sponge for pump-assisted separation and showed improved stress, strain, and toughness compared to neat CAB membrane. The results demonstrate a bio-based composite membrane platform for environmental remediation, oily wastewater treatment, and protection of aquatic and terrestrial ecosystems.