Bio-inspired fabrication of superhydrophilic and underwater superoleophobic alumina membranes for highly efficient oil/w
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Bio-inspired fabrication of superhydrophilic and underwater superoleophobic alumina membranes for highly efficient oil/ water separation Wenjin Zhou, Mingyang Zhou, Huapeng Zhang, Hongyan Tang
Ó American Coatings Association 2020 Abstract Inspired by fish scales, superhydrophilic and underwater superoleophobic alumina membranes were fabricated in this study. Dopamine deposited on the surface of alumina membranes through immersion over time, and then crosslinking reaction occurred with polyethyleneimine (PEI), which was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. It induced the modified layer coated on the membrane surface. Values of water contact angle of the modified alumina membranes were 0° in air. Values of underwater oil contact angle reached 155°, which indicated it was superhydrophilic and underwater superoleophobic. More particles engendered with the increase in the reaction time with PEI, which induced the decrease in the pore sizes and permeation flux. All values of oil rejection were higher than 98.5%. No obvious deterioration of permeation flux could be found. The rejection hardly suffered a sharp decline over 800 min. It indicates that the modified layer can firmly stick to the alumina membranes. Therefore, the as-prepared alumina membrane is promising for practical oil/water separation. Keywords Superhydrophilic, Underwater superoleophobic, Alumina membrane, Oil/water separation, Antifouling
Introduction In recent years, water pollution is becoming more and more serious. In particular, oily wastewater from oil spills and industrial oily wastewater has caused a serious ecological crisis, e.g., environmental polluW. Zhou, M. Zhou, H. Zhang, H. Tang (&) School of Materials Science and Engineering, Zhejiang SciTech University, Hangzhou 310018, China e-mail: [email protected]
tion and damage to public health. Oil/water separation becomes a worldwide challenge.1–7 Membrane separation technology is considered as a promising method for oily water separation due to its low operation cost and high separation efficiency, among some conventional methods.8–12 Superwetting membrane materials such as superhydrophilic and superhydrophobic membrane materials have exhibited extremely important applications in oil/water mixture.13 Oil can penetrate from superhydrophobic or underwater superoleophilic membrane materials, while water can be blocked. It is suitable for heavy oil/water separation (‘‘oil removing’’ type). General strategy is coating or grafting with fluorinated or siloxaned components on a support membrane.14–24 Sadeghi et al.14 fabricated electrospun membranes through blending fluorinated random copolymer and poly(vinylidene fluoride) (PVDF), which resulted in a hydrophobic and superoleophilic surface for oil/water separation. Wu et al.15 fabricated a flexible polydimethylsiloxane@multiwalled carbon nanotubes membrane with a water contact angle (WCA) of 167°, which was successfully applied to separate oil/water emulsions and exhibited excellent reusability
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