Acid, Alkali, and Abrasion-Resistant Nanofibrous Membranes Composed of ZIF-8 Metal–Organic Framework and Carbon Nanotubes for Oil–Water Separation

The treatment of oily wastewater remains a technological challenge. Membrane separation methods can offer solutions with high throughput and low operating cost if suitable membranes can be developed. In this work, an electrospun polymer composite membrane containing metal–organic framework (MOF) particles and carbon nanotubes (CNTs) is presented, which performs both high water flux and high separation efficiency. Polyacrylonitrile (PAN), which has excellent fiber-forming properties, is used as the polymer matrix. The MOF zeolitic imidazole framework-8 (ZIF-8) increases membrane hydrophilicity and imparts nanopores. The MOF particles are tightly associated with CNTs, increasing the MOF binding and providing mechanical stability and increased surface area to the composite fiber membrane. The result is a high-flux, high-separation efficiency, and recyclable polyacrylonitrile/zeolitic imidazolate framework-8/carbon nanotube (PAN/ZIF-8/CNT) nanofiber membrane. The membrane has a high water contact angle (WCA > 130°) and exhibits underwater oleophilicity and underoil hydrophobicity. The PAN/ZIF-8/CNT membrane has a hierarchical porous structure of microscale and nanoscale channels, resulting in good porosity that greatly improves oil–water separation performance. The membrane has a high separation flux of 2139 L m–2 h–1 for oil–water emulsion in a gravity-fed apparatus and excellent oil/water separation efficiency (>98.5%). In addition, even under acidic, alkaline, saline, and abrasive conditions, the prepared membrane also exhibits excellent hydrophobic and oleophilic properties. This work offers prospects for water purification and oily wastewater remediation.