Junwei Chen,Qianwen Yu,Mingxia Wang,Dan Liu,Linfang Dong,Zhenyu Cui,Benqiao He,Jianxin Li,Feng Yan
The treatment of various oily wastewaters generated in human production and life has been a huge challenge in recent years. Responsive materials for controlled wettability surface have a great potential for oil-water separation. Inspired by the superior pH-responsive of poly (2-( N, N′ -dimethylamino) ethyl methacrylate) (PDMAEMA), a pH-responsive self-cleaning PVDF ultrafiltration membrane containing both carboxyl and tertiary amine groups were prepared by a simple grafting and co-blending method. The membrane fabrication process consisted of introducing 3-Dimethylaminopropylamine (DMPA) into the SMA side chain, resulting in the creation of the amphiphilic polymer DMPA@SMA. This polymer was then mixed with PVDF to produce DMPA@SMA/PVDF membranes. The optimized DMPA@SMA/PVDF membranes showed excellent superhydrophilicity/underwater superhydrophobicity, with a water contact angle of 0° and an underwater oil contact angle higher than 150° for crude oil. These endowed the as prepared membrane with a high pure water flux of 852 L·m −2 ·h −1 and anti-crude-oil-adhesion property. The separation efficiency exceeded 98% for various surfactant-stabilized oil-in-water emulsions, whether it’s positively charged emulsion or negatively charged emulsion. More interestingly, the carboxyl and tertiary amine groups presented the membrane with pH responsivity, and the membrane surface can be triggered by acid or alkali with self-cleaning performance. Strategy proposed in the present work offers a convenient and effective way to prepare membranes treating oil-in-water emulsions with either negative or positive charges.
Using filtration materials possessing superhydrophilic-underwater superoleophobic property to separate oil/water mixtures has become a research hotspot. However, most of the works are concentrated on building filtration materials with special wettability , ignoring the pore structures . Herein, polydopamine-modified (PDA-modified) nanofibrous mats with tunable pore sizes and special wettability were prepared by combining the electrospinning technique with a very simple modification process for oil/water separation. The results indicated that the pore structure of the PDA-modified nanofibrous mats could be finely modulated by utilizing different kinds of stainless steel wire meshes as collectors, and more interesting was that all the modified nanofibrous mats showed superhydrophilicity-underwater superoleophobicity. For the oil/water separation, the PDA-modified nanofibrous mats displayed high efficiency and high flux in separating oil/water mixtures, and the water flux could be highly improved by controlling the pore size and the optimal flux was high up to 40,405 L m −2 h −1 . In addition, the PDA-modified nanofibrous mats exhibited excellent durability and recyclability. Finally, as a proof of concept a novel oil collection device based on the PDA-modified nanofibrous mat was constructed to in situ separate the oil/water mixtures and collect the oil simultaneously. The developed PDA-modified nanofibrous mats would have wide applications in oily wastewater separation and purification.
A new multifunctional KGM/PDA/PVDF composite membrane was successfully prepared via facile nonsolvent induced phase inversion method. Here, the KGM component consisted of numerous covalent bonds, which could improve the corrosion resistance of membrane materials. The dopamine, as a natural “glue” between PVDF substantial and KGM, is capable of integrating different materials together suitably. The as-prepared membrane possessed superior superhydrophilic/underwater superoleophobic property, great corrosion resistance and antifouling property. The separation efficiency was as high as 99.01%, and could stay relatively stable even in the acid, alkali or high salty environment. Additionally, the membrane had great regeneration performance and could keep stable after 15 cyclic separation, which was appropriate for efficient various oil–water separation process. Moreover, the composite membrane could also effectively separate dyes in different environments and the efficiencies were all more than 91%. All in all, the multifunctional composite membrane with facile preparation method might provide a promising strategy and significant theoretical basis for the efficient separation of oil–water emulsions and dyes.
Superwettable membranes with superhydrophilicity/underwater superoleophobicity (SHL/UWSOB) or hydrophobicity/underoil superhydrophobicity (HB/UOSHB) are considered critical components in the chemical industry. However, despite the unique wettability of these membranes, there are still challenges in meeting the needs of the developing society. Herein, a Janus nanofibrous membrane with a special micro-nanostructure was constructed by a bottom-up electrospinning strategy using two different precursors: zeolitic imidazolate framework-8-polyacrylonitrile/ N,N -dimethylformamide (ZIF-8-PAN/DMF) and candle soot-polyacrylonitrile/ N,N -dimethylformamide (CS-PAN/DMF). The PAN@ZIF-8 nanofibrous membrane exhibited HB/UOSHB, with water contact angles higher than 150° in oils, whereas the PAN@CS nanofibrous membrane displayed favorable SHL/UWSOB, with oil contact angles greater than 151° in water. Simultaneously, the resulting Janus nanofibrous membrane exhibited excellent rejection rate (99.1%) towards various oil–water emulsions and a high flux of up to 1720 ± 20 L m −2 h −1 driven only by gravity. The as-prepared Janus membrane was cycled five times without compromising the flux and rejection rate, demonstrating its satisfactory cycling stability. Comparative analysis demonstrated that the comprehensive separation performance of the resulting Janus nanofibrous membrane was superior to that of current homogeneous or other Janus membranes. More importantly, the as-prepared Janus membrane exhibited favorable chemical stability under harsh conditions (acidic and alkaline environments). This study presents a facile and efficient method for constructing a performance-stabilized Janus membrane, which can be utilized for multiple applications, such as oil–water separation, osmotic gasification, and seawater desalination.
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