Fabrication of durable super-hydrophilic/underwater super-oleophobic poly(arylene ether nitrile) composite membrane via biomimetic co-deposition for multi-component oily wastewater separation in harsh environments

Abstract

The polymer membranes with super-wetting surface have shown promising application for oily wastewater treatment. However, the synergistic separation of multi-component oily wastewater in harsh environments is still a big challenge. In this work, we demonstrated a facile strategy to construct the durable super-hydrophilic/underwater super-oleophobic PEN composite membrane for the synergistic treatment of oil-in-water emulsions and dye. First of all, based on the thermally stable carboxyl poly (aryl ether nitrile), the hydrophilic polymer membrane with rough trench surface was prepared by non-solvent phase conversion, using non-woven fabric (NWF) as template. Secondly, the TiO2 nanoparticles were firmly immobilized onto the membrane surface via biomimetic co-deposition of dopamine (DA), aminopropyltriethoxysilane (APTES), and TiO2 nanoparticles. Especially, the physical confinement effect of rough trench surface, strong adhesion of polydopamine, and chemical crosslinking between APTES and DA contributed to the stable super-wetting performance of composite membrane (CA: 0° and UOC: 151°). Meanwhile, the obtained super-wetting composite membrane exhibited promising synergistic separation performance of multi-component oily wastewater (oil-in-water emulsions and dye). For the separation of oil-in-water emulsions containing 50 ppm methylene blue, the flux and rejection ratio reached 552.25 ± 25 L/(m2 h) and 99.38 ± 1.3%, respectively. More importantly, the prepared composite membrane could keep stable super-wetting property and separation efficiency under high-temperature and corrosive environments (80 °C/4 M HCl and 80 °C/1 M NaOH). In addition, the low oil adhesion and high tensile strength endowed the composite membrane with high antifouling resistance and excellent recyclability for the separation of multi-component oily wastewater. This work provides an alternative platform for constructing durable super-wetting composite membrane, which shows the potential application for treating complicated oily wastewater of petro-chemistry industry in harsh environments.