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Human activities are producing increasing amounts of oily water. Therefore, methods for oil/water separation are attracting great attention. Membranes, including nanofibers for oil/water separation based on superwetting surfaces have advantages of low cost, high efficiency, and environmental friendliness. In addition to the common superhydrophobic and superhydrophilic surfaces, other novel superwetting membranes have been developed for oil/water separation. This review introduces and discusses membranes and nanofibers reported in recent years for oil/water separation, with emphasis on coupling the wettability characteristics with the structural features. We mainly discuss five types of membranes with superwetting surfaces. In each category, representative research, manufacturing technology, membrane structure, and applications are discussed in detail. Finally, the challenges and future opportunities for superwetting membranes in the field of oil/water separation are put forward. [ABSTRACT FROM AUTHOR]

In recent years, rare earth complexes have become famous for their unique luminescence characteristics, such as clear emission bands, long lifetimes, and high luminous quantum efficiency. Since lanthanide ions have relatively small absorption areas in the ultraviolet region, they absorb light weakly. However, the excitation can be improved via coordination with organic ligands and subsequent energy transfer from the ligand triplet state to a coordinated metal ion. Electrospinning is a processing method that can readily combine rare earth complexes with matrix materials, to obtain fiber membranes with high fluorescence efficiency and stable mechanical properties. Here, we report the application of fluorescent nanofibers to color-tunable materials and oxygen sensing materials by discussing the electrospinning techniques used to produce electrospun nanofibers containing lanthanide complexes. We then focus on the mechanism of luminescence of fluorescent nanofibers, discussing polymer-based membranes and ceramic-based membranes based on the main constituent materials of the fiber membranes. [ABSTRACT FROM AUTHOR]

In the past few decades, due to the rapid development of industry and the rapid growth of population, emissions of pollutants to the environment have increased dramatically, and the demand for drinking water is also increasing. Water treatment is a matter of concern because it is directly related to the health of humans and wildlife. Graphene and its derivatives have potential applications in seawater desalination and wastewater treatment due to their unique pore structure and ionic molecular sieving separation capabilities. Graphene, graphene oxide (GO), and reduced graphene oxide (rGO) can be formulated into nanoporous materials and composites with tunable properties that can be optimized for water filtration. Methods for perforating graphene include ion etching/ion bombardment and electron beam nanometer engraving, which are briefly introduced in this paper. Graphene-based composites further expand the capabilities of graphene in seawater desalination and wastewater treatment, by introducing new features and properties. In this review, the performance improvement of graphene-based separation membranes in decontamination and desalination in recent years is reviewed in detail. This review focuses on improving the performance of graphene-based membranes for separation, decontamination, and seawater desalination applications, by discussing how various modifications and preparation methods impact important performance properties, including water permeance, selectivity, rejection of solutes, membrane mechanical strength, and antifouling characteristics. We also discuss the outlook for future development of graphene-based membranes. [ABSTRACT FROM AUTHOR]

Water shortages have become a major problem facing the world today. Membrane separation technology is commonly used in water treatment applications. The development of new materials for water treatment can reduce the energy required for water treatment, reduce cost, and improve efficiency. The unique structure and properties of graphene and silica make them attractive materials for preparation of nanofiltration membranes for water treatment. We have successfully prepared a graphene oxide/silica (GO/SiO2) hybrid composite materials by in situ hydrolysis, using tetraethyl orthosilicate (TEOS) as a silicon source in an alkaline environment. The chemistry and structure of these materials are characterized by TEM, FTIR, Raman, and XPS of GO and the GO/SiO2 composite. BET porosimetry reveals that the total pore volume of the composite is 2.84 cm3 g−1, the specific surface area is 2897 m2 g−1, and the average pore diameter is 3.97 nm. We prepared GO membranes and GO/SiO2 composite membranes by vacuum suction filtration. The morphology of the membrane was observed by FESEM and AFM. The composite membrane has a larger surface roughness (Rms = 9.39). We also tested the thermal stability by TGA, and hydrophilicity by water contact angle measurements. The water permeance of the composite membrane is up to 229.15 L m−2 h−1 bar−1, and the rejection of the rhodamine B dye molecules is as high as 99%. The GO/SiO2 hybrid composite membrane has good hydrophilicity and thermal stability, high water permeance and rejection, and can be developed as a high-performance material for water treatment. [ABSTRACT FROM AUTHOR]

To obtain nanofiltration membranes with high-performance in desalination and water purification, membranes of graphene oxide (GO), reduced graphene oxide (rGO) and GO/polyacrylamide (PAM) are prepared by a vacuum filtration method. This method is conducted in aqueous solution without any organic solvents. The graphene-based membranes (GBMs) are characterized by UV-visible spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscopy, atomic force microscopy, scanning electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy. The hydrophilicity of GBMs is also evaluated by contact angle measurement. The interlayer spacing of GO membrane (0.85 nm), GO/PAM membrane (0.68 nm) and rGO membrane (0.36 nm) are measured by X-ray diffraction. The performance of the GBMs is evaluated on a dead-end filtration device. The water flux and retention of rhodamine B of the membranes are 399.04 L m−2 h−1 bar−1 and 85.03% (GO), 188.89 L m−2 h−1 bar−1 and 95.43% (GO/PAM), 85.85 L m−2 h−1 bar−1 and 97.06% (rGO), respectively. The GO/PAM membrane has the best comprehensive separation performance because of its proper interlayer spacing. GO/PAM membranes provide potential advantages in the design of high-performance membranes for molecular separation and water purification. [ABSTRACT FROM AUTHOR]