Green and robust superhydrophilic electrospun stereocomplex polylactide membranes: Multifunctional oil/water separation and self-cleaning

Asymmetric Sc-PLA Membrane with Multi-scale Microstructures: Wettability, Antifouling, and Oil-Water Separation

In this work, an eco-friendly superhydrophobic stereo-complex polylactic acid (Sc-PLA) membrane was fabricated by a facile non-solvent-induced phase separation (NIPS) method, followed by peeling off its skin layer. By adjusting the thickness and roughness, membranes with various multi-scale microstructures could be obtained due to the formation of stereo-complex crystals during the process of phase separation. The Sc-PLA membranes display a hydrophobic wetting property. Interestingly, when the skin layer of the membrane with a 600 μm thickness was peeled off, the water contact angle on the surface of the membrane significantly improved from 142 to 152°, and the membrane displayed superhydrophobic wetting properties, which may be owing to the improvement of roughness for the surface by enlarging the exposure opportunity of finger holes and microstructures. In addition, the Sc-PLA membrane with superhydrophobicity shows excellent antifouling performance and large oil absorption capacity. Predictably, the Sc-PLA membranes may have potential applications in antifouling and oil-water separation.

Multifunctional membranes with super-wetting characteristics for oil-water separation and removal of hazardous environmental pollutants from water: A review

Over the past few years, oil-water separation techniques have been widely researched due to influences of oil pollution. The oil pollution is significantly increasing day-by-day because of ever-increasing usage of oil in daily routine of humans and industrial activities. The separation of water from oil-water emulsions/mixtures through membrane technology has provided absolute necessary qualities such as low cost, eco-friendly, easy-operation and energy efficient. To build up the filter membranes with special super-wettability properties and bearing excellent multifunctional applications is highly attractive research area in current decade. However, evolution of membrane technology suffered many deficiencies including severe fouling, short-standing against high flow speed, surface wettability disorders, non-reusable and limited application. In this review article, we outline the recent advances in membrane technology with respect to special super-wettability properties, enhanced characteristics for purpose to serve oil-water separation, and more specifically its multifunctional applications. Therefore, this study is made for membranes having other than applications, in addition to oil-water separation. Further, the wetting phenomenon of these multifunctional membranes is addressed and highlighted the brief overview of surface wetting types including Superhydrophobic-Superoleophilic membranes, Superhydrophilic-Superoleophobic membranes, and Superhydrophilic-underwater Superoleophobic membranes. Moreover, relative fabrication procedures and multifunctional applications of developed multifunctional super-wetting membranes are also discussed along with wetting behavior. Finally, the current developments and achievements for oil-water separation multifunctional super-wetting membranes are concluded. Besides, it also explores the future challenges and obstacles associated to these membranes. Hence, this article provides brief overview of advancement of oil-water separation based multifunctional super-wetting membranes and ended with new thoughts of further modification/enhancement.

In situ growth polydopamine decorated polypropylen melt-blown membrane for highly efficient oil/water separation

The removal of organic pollutants from water is highly desired because of the development of industrial and social economy. Superhydrophilic and underwater superoleophobic membranes are emerging materials for effective oil/water separation. In this paper, superhydrophilic and underwater superoleophobic polypropylene (PP) melt-blown membranes were prepared through melt-blown and in situ growth method, achieving highly efficient oil/water separation. After in situ growth, polydopamine (PDA) grows on the surface of PP fibers, and the addition of coupling agent (3-aminopropyltriethoxysilane, APTES) can improve the stability of the membrane in harsh environments (1 M HCl, 1 M NaOH, 1 M NaCl). The PDA/APTES@PP membrane could dramatically enhance the wetting (water contact angle ∼0, underwater oil contact angle∼154°) compare with the pristine PP melt-blown membrane (water contact angle ∼130°, underwater oil contact angle ∼0). Moreover, the filtration performance is at a high level (∼99%). The behaviors are comparable or even superior to the typical reported results in the references (such as the mussel-inspired superhydrophilic PVDF membrane and copper mesh). This method provides a facile route to prepared multi-functional membrane for highly efficiency oil/water separation and industrial oily wastewater remediation.

3D network super-hydrophobic hexafluorbisphenol A poly(aryl ether ketone) membrane prepared by one-step electrospraying

Novel super-hydrophobic poly(aryl ether ketone) (PAEK) membranes have been firstly prepared by modifying ordinary PAEK into hexafluorbisphenol A-PAEK through traditional nucleophilic condensation polymerization and subsequently simple electrospraying technique. With the solution concentration increased, the micromorphology exhibited nanofibers, nanofiber with spindles, 3D network with microspheres embedded, microspheres and dense films, successively. The static water contact angle increased from 99° to 155°, while the sliding angle from 1.3° to 6.8° (±1°), in which the 3D network presented the strongest super-hydrophobicity. After 200 h of water flushing, the rough surface structure and super-hydrophobicity of the membranes were well retained. Moreover, the membrane exhibited wonderful self-cleaning property, oil/water separation property, and stability due to the hierarchical micro/nanostructures. This work provides a new route for the creation of super-hydrophobic high performance engineering plastic fabrics with the potential values in large-scale application of filtration, oil/water separation, and antifouling.

Zwitterionic Polymer-Grafted Superhydrophilic and Superoleophobic Silk Fabrics for Anti-Oil Applications

A highly anti-oil fabric membrane is synthesized by surface grafting of zwitterionic poly(sulfobetaine methacrylate) (PSBMA) onto the fabric surface. The fabric membrane is first enzymatically modified to create more reactive amine groups on the surface. A surface-initiated atom transfer radical polymerization (SI-ATRP) reaction is then performed to modify the fabric membrane surface with a dense PSBMA brush layer. Surface characterization indicates that the brush-grafted fabric membrane exhibits increased surface roughness and improved superhydrophilicity. The PSBMA-modified silk fabrics show a very large contact angle for oil droplets in water, and have excellent oil resistance in air and in water-oil mixtures.