Calcinable Polymer Membrane with Revivability for Efficient Oily‐Water Remediation

Fouling of polymeric membranes remains a major challenge for long‐term operation of oily‐water remediation. The common reclamation methods to recycle fouled membranes have the issues of either incomplete degradation of organic pollutants or damage to filter membranes. Here, a calcinable polymer membrane with effective reclamation after fouling is reported, which shows full recovery of the original oil/water separation efficiency. The membrane is made of polysulfonamide/polyacrylonitrile fibers by emulsion electrospinning, followed by hydrothermal decoration of TiO₂ nanoparticles. The bonding structured fibrous membrane displays outstanding thermal stability in air (400 °C), strong acid/alkali resistance (at the pH range from 1 to 13), and robust tensile strength. As a result, the chemically fouled polymeric membrane can be easily reclaimed without decreasing in separation performance and mechanical properties by annealing treatment. As a proof‐of‐concept, the as‐prepared membrane is integrated into a wastewater separation tank, which achieves a high water flux over 3000 L m^?2 h^?1 and oil rejection efficiency of 99.6% for various oil‐in‐water emulsions. The presented strategy on membrane fabrication is believed to be an effective remedy for membrane fouling, and should apply in a wider field of filtration industry.     

Ultrafiltration Membranes with Structure‐Optimized Graphene‐Oxide Coatings for Antifouling Oil/Water Separation

Fouling of ultrafiltration (UF) membranes in oil/water separation is a long‐standing issue and a major economic barrier to their use in a broad range of applications. Currently reported membranes typically show severe fouling, resulting from the strong oil adhesion on the membrane surface and/or oil penetration inside the membranes. This greatly degrades their performance and shortens service lifetime. Here, the use of graphene oxide (GO) as a novel coating material for the fabrication of fully recoverable, UF membranes with desired hierarchical surface roughness is accomplished by a facile vacuum filtration method for antifouling oil/water separation. The combination of ultrathin, “water‐locking” GO coatings with the optimized hierarchical surface roughness, provided by the inherent roughness of the porous supports and the corrugation of the GO coatings, minimizes underwater oil adhesion on the membrane surface. Cyclic membrane performance evaluation tests revealed approximately 100% membrane recovery by facile surface water flushing, establishing their excellent easy‐to‐recover capability. The novel GO functional coatings with optimized hierarchical structures may have broad applications in oil‐polluted environments.     

Dual‐Layer Superamphiphobic/Superhydrophobic‐Oleophilic Nanofibrous Membranes with Unidirectional Oil‐Transport Ability and Strengthened Oil–Water Separation Performance

Thin porous membranes with unidirectional oil‐transport capacity offer great opportunities for intelligent manipulation of oil fluids and development of advanced membrane technologies. However, directional oil‐transport membranes and their unique membrane properties have seldom been reported in research literature. Here, it is proven that a dual‐layer nanofibrous membrane comprising a layer of superamphiphobic nanofibers and a layer of superhydrophobic oleophilic nanofibers has an unexpected directional oil‐transport ability, but is highly superhydrophobic to liquid water. This novel fibrous membrane is prepared by a layered electrospinning technique using poly(vinylidene fluoride‐hexafluoropropylene) (PVDF‐HFP), PVDP‐HFP containing well‐dispersed FD‐POSS (fluorinated decyl polyhedral oligomeric silsesquioxanes), and FAS (fluorinated alkyl silane) as materials. The directional oil‐transport is selective only to oil fluids with a surface tension in the range of 23.8–34.0 mN m^–1. By using a mixture of diesel and water, it is further proven that this dual‐layer nanofibrous membrane has a higher diesel–water separation ability than the single‐layer nanofiber membranes. This novel nanofibrous membrane and the incredible oil‐transport ability may lead to the development of intelligent membrane materials and advanced oil–water separation technologies for diverse applications in daily life and industry.     

Underwater Self‐Cleaning PEDOT‐PSS Hydrogel Mesh for Effective Separation of Corrosive and Hot Oil/Water Mixtures

Oil‐polluted water is a worldwide problem due to the increasing industry oily wastewater and the frequent oil‐spill pollution. Here, PEDOT‐PSS hydrogel meshes are successfully prepared by using in‐situ chemical polymerization on Ti mesh substrate, which are composed of hierarchical porous structures and present superhydrophilicity in air and superoleophobicity underwater. And PEDOT‐PSS hydrogel meshes exhibit excellent environmental stability under a series of harsh conditions, which are used for the separation of the mixtures of oil and various corrosive and active aqueous solutions, including strong acidic, alkaline, or salt aqueous solutions, even hot‐water. The hydrogel meshes offer high separation efficiency of up to 99.9%. Importantly, the mesh still reveals 99.5% separation efficiency even after 50 times separation operation, demonstrating its excellent durability that shows attractive potential for practical oil‐water separation in industry and everyday life.     

Preparation of Superhydrophilic and Underwater Superoleophobic Nanofiber‐Based Meshes from Waste Glass for Multifunctional Oil/Water Separation

The deterioration of water resources due to oil pollution, arising from oil spills, industrial oily wastewater discharge, etc., urgently requires the development of novel functional materials for highly efficient water remediation. Recently, superhydrophilic and underwater superoleophobic materials have drawn significant attention due to their low oil adhesion and selective oil/water separation. However, it is still a challenge to prepare low‐cost, environmentally friendly, and multifunctional materials with superhydrophilicity and underwater superoleophobicity, which can be stably used for oil/water separation under harsh working conditions. Here, the preparation of nanofiber‐based meshes derived from waste glass through a green and sustainable route is demonstrated. The resulting meshes exhibit excellent performance in the selective separation of a wide range of oil/water mixtures. Importantly, these meshes can also maintain the superwetting property and high oil/water separation efficiency under various harsh conditions. Furthermore, the as‐prepared mesh can remove water‐soluble contaminants simultaneously during the oil/water separation process, leading to multifunctional water purification. The low‐cost and environmentally friendly fabrication, harsh‐environment resistance, and multifunctional characteristics make these nanofiber‐based meshes promising toward oil/water separation under practical conditions.     

膜技术处理含油废水的研究

介绍了膜技术在含油废水处理中的特点和应用前景,针对含油废水的性质,探讨了膜类型的选择、操作压差、膜面流速、操作温度、膜污染及清洗等因素对膜技术处理含油废水的影响.通常情况下,操作压力过大时,膜通量随压力变化较小,而低于该压力时,膜通量随操作压力的增大而提高;膜面流速和温度对膜通量的影响和操作压力的影响类似;膜经过合适的清洗可以基本恢复膜通量.还介绍了膜技术在油田含油废水处理中的实例和存在的问题,并进一步指出今后的发展方向是研究开发经济、高效的污水处理技术,尤其是膜技术和微生物法结合处理油田含油废水的技术.     

MOF‐Based Hierarchical Structures for Solar‐Thermal Clean Water Production

Solar‐thermal water evaporation, as a promising method for clean water production, has attracted increasing attention. However, solar water evaporators that exhibit both high water vapor generation ability and anti‐oil‐fouling ability have not been reported. Here, a unique metal–organic‐framework‐based hierarchical structure, referred to as MOF‐based hierarchical structure (MHS), is rationally designed and prepared, which simultaneously displays a high solar absorption and a superhydrophilic and underwater superoleophobic surface property. As a proof‐of‐concept application, a device prepared from the MHS can achieve a high solar‐thermal water evaporation rate of 1.50 kg m^?2 h^?1 under 1 sun illumination. Importantly, the MHS also possesses an excellent anti‐oil‐fouling property, ensuring its superior water evaporation performance even in oil‐contaminated water. The high solar‐thermal water evaporation rate and anti‐oil‐fouling property make the MHS a promising material for the solar‐thermal water production.     

A Self-Cleaning Heterostructured Membrane for Efficient Oil-in-Water Emulsion Separation with Stable Flux

Lack of clean water is a major global challenge. Membrane separation technology is an ideal choice for the treatment of industrial, domestic sewage owing to its low energy consumption and cost. However, membranes are highly susceptible to contamination, particularly during wastewater treatment, which has limited their practical applications in this field. Similarly, the flux of the membrane decreases with prolonged use due to its reduced interlayer spacing. Preparation of membranes with anticontamination properties and stable flux is the key to addressing this problem. In this study, a 2D heterostructure membrane with visible-light-driven self-cleaning performance is prepared via a self-assembly process. Notably, the addition of palygorskite increases the interlayer spacing of the graphene and heterojunction structures, which increases the flux of the membrane and avoids a decrease of the interlayer spacing of the membrane under pressure. The presence of a heterojunction with visible light catalytic properties effectively avoids membrane fouling and avoids a sharp decrease of the permeation flux. Importantly, the prepared 2D membrane has excellent separation performance for oil–water emulsions with both high flux and efficiency. These features suggest great potential for the prepared 2D membrane in wastewater treatment applications.     

3D‐Printed Biomimetic Super‐Hydrophobic Structure for Microdroplet Manipulation and Oil/Water Separation

Biomimetic functional surfaces are attracting increasing attention for various technological applications, especially the superhydrophobic surfaces inspired by plant leaves. However, the replication of the complex hierarchical microstructures is limited by the traditional fabrication techniques. In this paper, superhydrophobic micro‐scale artificial hairs with eggbeater heads inspired by Salvinia molesta leaf was fabricated by the Immersed surface accumulation three dimensional (3D) printing process. Multi‐walled carbon nanotubes were added to the photocurable resins to enhance the surface roughness and mechanical strength of the microstructures. The 3D printed eggbeater surface reveals interesting properties in terms of superhydrophobilicity and petal effect. The results show that a hydrophilic material can macroscopically behave as hydrophobic if a surface has proper microstructured features. The controllable adhesive force (from 23 μN to 55 μN) can be easily tuned with different number of eggbeater arms for potential applications such as micro hand for droplet manipulation. Furthermore, a new energy‐efficient oil/water separation solution based on our biomimetic structures was demonstrated. The results show that the 3D‐printed eggbeater structure could have numerous applications, including water droplet manipulation, 3D cell culture, micro reactor, oil spill clean‐up, and oil/water separation.     

Robust fabrication of fluorine-free superhydrophobic steel mesh for efficient oil/water separation

A facile and environmentally friendly method was reported for the fabrication of superhydrophobic steel mesh by depositing with dual-scale Polystyrene@Silica (PS@SiO₂) particles coated with hexadecyltrimethoxysilane (HDTMS), which provided 3D multi-scale hierarchical rough surface structure with low surface energy to perform the superhydrophobic effect. PS particles of ~1 μm and ~200 nm were first synthesized via dispersion polymerization and emulsion polymerization, respectively. The obtained PS particles were then used as template for the silification using tetraethyl orthosilicate as the precursor. After treated with HDTMS, the PS@SiO₂ particles were deposited on steel mesh forming dual-sized hierarchical structures. The as-prepared film exhibited excellent water repellence with a water contact angle of 161.6° ± 1.1° and water contact angle hysteresis of 3.4°. It also showed efficient and rapid oil/water separation ability and could be repeatedly used for at least 5 times. This facile synthesis strategy for fabricating multifunctional steel mesh provides potential applications in large-scale oil–water separation.     

膜技术在含油废水处理中的应用

介绍了超滤、反渗透等膜分离技术在含油废水处理中的应用,分析了膜分离技术处理含油废水的效果及透过特性,并且给出了它们在含油废水处理中的应用实例．     

High Virus Removal by Self‐Organized Nanostructured 2D Liquid‐Crystalline Smectic Membranes for Water Treatment

To obtain high quality of drinking water free from biocontaminants is especially important issue. A new strategy employing smectic liquid‐crystalline ionic membranes exhibiting 2D structures of layered nanochannels for water treatment is proposed for efficient virus removal and sufficient water flux. The smectic A (SmA) liquid‐crystalline membranes obtained by in situ polymerization of an ionic mesogenic monomer are examined for removal of three distinct viruses with small size: Qβ bacteriophage, MS2 bacteriophage, and Aichi virus. The semi‐bilayer structure of the SmA significantly obstructs the virus penetration with an average log reduction value of 7.3 log₁₀ or the equivalent of reducing 18 million viruses down to 1. Furthermore, the layered nanochannels of the SmA liquid crystal allow efficient water permeation compared to other types of liquid‐crystalline membrane consisting of nanopores.     

Robust Flower‐Like TiO2@Cotton Fabrics with Special Wettability for Effective Self‐Cleaning and Versatile Oil/Water Separation

Inspired by the hierarchical structure of the mastoid on the micrometer and nanometer scale and the waxy crystals of the mastoid on natural lotus surfaces, a facile one‐step hydrothermal strategy is developed to coat flower‐like hierarchical TiO₂ micro/nanoparticles onto cotton fabric substrates (TiO₂@Cotton). Furthermore, robust superhydrophobic TiO₂@Cotton surfaces are constructed by the combination of hierarchical structure creation and low surface energy material modification, which allows versatility for self‐cleaning, laundering durability, and oil/water separation. Compared with hydrophobic cotton fabric, the TiO₂@Cotton exhibits a superior antiwetting and self‐cleaning property with a contact angle (CA) lager than 160° and a sliding angle lower than 5°. The superhydrophobic TiO₂@Cotton shows excellent laundering durability against mechanical abrasion without an apparent reduction of the water contact angle. Moreover, the micro/nanoscale hierarchical structured cotton fabrics with special wettability are demonstrated to selectively collect oil from oil/water mixtures efficiently under various conditions (e.g., floating oil layer or underwater oil droplet or even oil/water mixtures). In addition, it is expected that this facile strategy can be widely used to construct multifunctional fabrics with excellent self‐cleaning, laundering durability, and oil/water separation. The work would also be helpful to design and develop new underwater superoleophobic/superoleophilic materials and microfluidic management devices.     

新型TiO2光催化复合分离膜研究进展

TiO2光催化复合分离膜是近几年出现的一种集光催化和膜分离作用于一体的新型多功能复合膜,多用于水处理中.将光催化剂TiO2负载于膜表面或者内嵌于膜中,制备成光催化复合分离膜,不仅解决了TiO2的回收问题,且能在一定程度上缓解或者消除膜污染问题;在发挥光催化和膜分离作用的同时,还能产生一系列的协同作用,以加强污染物的处理...     

改性聚偏氟乙烯膜的油吸附性研究

排除因液体流动和压力梯度造成的浓差极化、油滴形变等影响因素,用静态吸附法考察膜对油分子的吸附规律.结果表明,膜对油分子的吸附属于一级动力学吸附,吸附过程的主要控制步骤是油分子在膜表面及膜孔内的扩散.Freundlich等温方程可以很好地描述膜对油分子的吸附,拟合后的常数K和1/n均较小,证明所用的改性聚偏氟乙烯膜对油分子的吸附能力较小,吸附强度较弱,也即改性聚偏氟乙烯膜耐污染,且易清洗.膜改性可以在处理低浓度含油废水时有效减少由于膜对油分子的吸附而造成的污染.     

Progressive Design of Plasmonic Metal–Semiconductor Ensemble toward Regulated Charge Flow and Improved Vis–NIR‐Driven Solar‐to‐Chemical Conversion

Surface plasmon resonance (SPR)‐mediated photocatalysis without the bandgap limitations of traditional semiconductor has aroused significant attention in solar‐to‐chemical energy conversion. However, the photocatalytic efficiency barely initiated by the SPR effects is still challenged by the low concentration and ineffective extraction of energetic hot electrons, slow charge migration rates, random charge diffusion directions, and the lack of highly active sites for redox reactions. Here, the tunable, progressive harvesting of visible‐to‐near infrared light (vis–NIR, λ > 570 nm) by designing plasmonic Au nanorods and metal (Au, Ag, or Pt) nanoparticle codecorated 1D CdS nanowire (1D CdS NW) ensemble is reported. The intimate integration of these metal nanostructures with 1D CdS NWs promotes the extraction and manipulated directional separation and migration of hot charge carriers in a more effective manner. Such cooperative synergy with tunable control of interfacial interaction, morphology optimization, and cocatalyst strategy results in the distinctly boosted performance for vis–NIR‐driven plasmonic photocatalysis. This work highlights the significance of rationally progressive design of plasmonic metal–semiconductor‐based composite system for boosting the regulated directional flow of hot charge carrier and thus the more efficient use of broad‐spectrum solar energy conversion.     

3D Printing All‐Aromatic Polyimides using Mask‐Projection Stereolithography: Processing the Nonprocessable

High‐performance, all‐aromatic, insoluble, engineering thermoplastic polyimides, such as pyromellitic dianhydride and 4,4′‐oxydianiline (PMDA–ODA) (Kapton), exhibit exceptional thermal stability (up to ≈600 °C) and mechanical properties (Young's modulus exceeding 2 GPa). However, their thermal resistance, which is a consequence of the all‐aromatic molecular structure, prohibits processing using conventional techniques. Previous reports describe an energy‐intensive sintering technique as an alternative technique for processing polyimides with limited resolution and part fidelity. This study demonstrates the unprecedented 3D printing of PMDA–ODA using mask‐projection stereolithography, and the preparation of high‐resolution 3D structures without sacrificing bulk material properties. Synthesis of a soluble precursor polymer containing photo‐crosslinkable acrylate groups enables light‐induced, chemical crosslinking for spatial control in the gel state. Postprinting thermal treatment transforms the crosslinked precursor polymer to PMDA–ODA. The dimensional shrinkage is isotropic, and postprocessing preserves geometric integrity. Furthermore, large‐area mask‐projection scanning stereolithography demonstrates the scalability of 3D structures. These unique high‐performance 3D structures offer potential in fields ranging from water filtration and gas separation to automotive and aerospace technologies.     

2D Porous TiO2 Single‐Crystalline Nanostructure Demonstrating High Photo‐Electrochemical Water Splitting Performance

Porous single crystals are promising candidates for solar fuel production owing to their long range charge diffusion length, structural coherence, and sufficient reactive sites. Here, a simple template‐free method of growing a selectively branched, 2D anatase TiO₂ porous single crystalline nanostructure (PSN) on fluorine‐doped tin oxide substrate is demonstrated. An innovative ion exchange–induced pore‐forming process is designed to successfully create high porosity in the single‐crystalline nanostructure with retention of excellent charge mobility and no detriment to crystal structure. PSN TiO₂ film delivers a photocurrent of 1.02 mA cm^?2 at a very low potential of 0.4 V versus reversible hydrogen electrode (RHE) for photo‐electrochemical water splitting, closing to the theoretical value of TiO₂ (1.12 mA cm^?2). Moreover, the current–potential curve featuring a small potential window from 0.1 to 0.4 V versus RHE under one‐sun illumination has a near‐ideal shape predicted by the Gartner Model, revealing that the charge separation and surface reaction on the PSN TiO₂ photoanode are very efficient. The photo‐electrochemical water splitting performance of the films indicates that the ion exchange–assisted synthesis strategy is effective in creating large surface area and single‐crystalline porous photoelectrodes for efficient solar energy conversion.     

Multichannel Charge Transfer and Mechanistic Insight in Metal Decorated 2D–2D Bi2WO6–TiO2 Cascade with Enhanced Photocatalytic Performance

Promising semiconductor‐based photocatalysis toward achieving efficient solar‐to‐chemical energy conversion is an ideal strategy in response to the growing worldwide energy crisis, which however is often practically limited by the insufficient photoinduced charge‐carrier separation. Here, a rational cascade engineering of Au nanoparticles (NPs) decorated 2D/2D Bi₂WO₆–TiO₂ (B–T) binanosheets to foster the photocatalytic efficiency through the manipulated flow of multichannel‐enhanced charge‐carrier separation and transfer is reported. Mechanistic characterizations and control experiments, in combination with comparative studies over plasmonic Au/Ag NPs and nonplasmonic Pt NPs decorated 2D/2D B–T composites, together demonstrate the cooperative synergy effect of multiple charge‐carrier transfer channels in such binanosheets‐based ternary composites, including Z‐scheme charge transfer, “electron sink,” and surface plasmon resonance effect, which integratively leads to the boosted photocatalytic performance.     

特异润湿型油水分离材料的研究进展

近年来,海上石油泄漏事故和各种含油有害污水排放日益频繁,不仅造成了严重的环境污染,同时也危及到人类健康。因此,如何高效分离油水混合物成为当前材料学领域一个亟待解决的问题和研究热点。目前,具有被油或水所选择性润湿的特异浸润性材料已被广泛应用于油水分离,它们具有高效的油水分离效果,应用前景相当广阔。综述了近年来各类新型、高效的特异润湿型油水分离材料的制备方法及其吸油能力、分离效率以及重复使用性能,总结了油水分离材料领域的研究现状及尚待解决的难点,同时也展望了该领域未来研究的热点及发展方向。