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Preparing easily scaled up, cost-effective, and recyclable membranes for separation technology is challenging. In the present study, a unique and new type of modified polyvinylidene fluoride (PVDF) nanofibrous membrane was prepared for the separation of oil-water emulsions. Surface modification was done in two steps. In the first step, dehydrofluor...
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The effect of a N,N-dimethylformamide (DMF)/acetone solvent system (3:7, 4:6, 5:5, 6:4, 7:3) and spinning medium (air and water) on the membrane morphology and the structure-property relationship were investigated. A facile method was optimized to generate a porous, polymer-fiber membrane via the combinative effect of electrospinning and thermally...
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... ES can produce nanofibers or nanofiber mats from several polymers and/or polymer blends [5,6] with the incorporation of several metallic and non-metallic oxide nanomaterials [7][8][9] or molecules with functional properties into systems [10][11][12]. Material composition and applications play a significant role in the performance of the nanofibers, for example, in biomedical applications [13][14][15], gas and fluid filtration [16][17][18], energy harvesting and storage, such as the production of hydrogen (H 2 ) [19][20][21], oil-water separation, water purification, and environmental protection [22][23][24][25], catalytic applications [26][27][28], food packaging [29], protein adsorption [30], waterproof and breathable clothing [31], sensors [32], optical applications [33], and lithium-ion batteries [34]. ...
This study investigated the impact of adding zinc oxide nanoparticles (ZnO-NPs) to electrospun membranes and cast films made of poly(ε-caprolactone) (PCL). The physicochemical, mechanical, and morphological properties of the samples were analyzed. Physicochemical parameters included water contact angle (WCA), water vapor transmission rate (WVTR), permeance, water vapor permeability (WVP), light transmission (T600), and transparency (T). Mechanical properties, such as maximum stress (Ϭmax), elongation (εmax), and Young’s modulus (MPa), were also evaluated. Morphological properties were analyzed in terms of thickness, dispersion, and surface roughness (measured by the arithmetic (Ra) and quadratic (Rq) averages). The crystallinity and melting point, as well as the functional DPPH• scavenging percentage (SP%), were also studied. The results showed that adding 1 wt% ZnO-NPs improved the water barrier properties of PCL membranes and films, increasing WCA by 1%–6% and decreasing WVTR by 11%–19%, permeance by 34%–20%, and WVP by 4%–11%, respectively. The T600 values of PCL/ZnO-NPs membranes and films were 2–3 times lower than those of neat PCL samples, indicating improved optical properties. The mechanical properties of the composite membranes and films also improved, with Ϭmax increasing by 56%–32% and Young’s modulus increasing by 91%–95%, while εmax decreased by 79%–57%. The incorporation of ZnO-NPs also increased the thickness and surface roughness of the samples. The SP% of PCL/ZnO-NPs increased by almost 69%, demonstrating the beneficial effects of ZnO-NPs on the system. These findings suggest that incorporating ZnO-NPs into PCL membranes and films can enhance their properties, making them well suited for various applications, such as those within the realm of materials science and nanotechnology.
... The resultant membrane showed high surface hydrophilicity and organic/bio-fouling resistance [8]. Similarly, incorporating nanoparticles into the PVDF membrane increased membrane hydrophilicity and enhanced membrane fouling resistance [9][10][11].On the other hand, Zhang et al. demonstrated that membrane surface hydrophilicity/hydrophobicity was not directly important to the interfacial interactions with sludge particles, although a high zeta potential and a particular roughness greatly reduced membrane fouling. [12]. ...
Graphical abstract 1 Research Paper Hydrophilic additives Microfiltration membrane Non-solvent-induced phase separation PVDF PEG • Membranes were fabricated by the non-solvent induced phase separation (NIPS) method. • The SEM images showed thick skin on the upper and macro-voids in the lower layer. • The expected performance could not be reached because the PEG leaked from the membrane.
... Among these new membrane materials, the application of superhydrophilic/superhydrophobic, superlipophilic/superhydrophobic, and underwater superhydrophobic/superhydrophobic materials are effective methods to achieve oil-water separation. For example, modified textile membrane (Dmitrieva et al., 2022), polymer film membrane (Bhagyaraj et al., 2021), Janus membrane , organic molecular membrane (Mohammed et al., 2022), nanofiber membrane (Boyraz et al., 2019), cellulose membrane (Halim et al., 2022), composite material membrane (Wen et al., 2022), aerogel membrane , and metal mesh (Cheng et al., 2017) have been successfully used to separate oil from water, which process can be carried out without additional power. Most of the traditional separation methods have problems such as low separation efficiency, limitation to small-scale operation, and facile secondary pollution. ...
In the development and production process of domestic and foreign oil fields, large amounts of oil-bearing wastewater with complex compositions containing toxic and harmful pollutants are generated. These oil-bearing wastewaters will cause serious environmental pollution if they are not effectively treated before discharge. Among these wastewaters, the oily sewage produced in the process of oilfield exploitation has the largest content of oil-water emulsion. In order to solve the problem of oil-water separation of oily sewage, the paper summarizes the research of many scholars in many aspects, such as the use of physical and chemical methods such as air flotation and flocculation, or the use of mechanical methods such as centrifuges and oil booms for sewage treatment. Comprehensive analysis shows that among these oil-water separation methods, membrane separation technology has higher separation efficiency in the separation of general oil-water emulsions than other methods and also exhibits a better separation effect for stable emulsions, which has a broader application prospect for future developments. To present the characteristics of different types of membranes more intuitively, this paper describes the applicable conditions and characteristics of various types of membranes in detail, summarizes the shortcomings of existing membrane separation technologies, and offers prospects for future research directions.
... These results indicate the potential for molecular membrane grafting for separation and purification [89]. The properties of the PVDF can be tuned for desired applications using a range of polymeric aninorganicic materials, including amino silanes [89], alkylamines [90], and titanium oxide [91], hydrophilic layers, dopamine [92], cellulose [93], and another polymer mixing [94]. ...
Periodical oil spills and massive production of industrial oil wastewater have impacted the aquatic environment and has put the sustainability of the ecosystem at risk. Oil-water separation has emerged as one of the hot areas of research due to its high environmental and societal significance. Special wettable membranes have received significant attention due to their outstanding selectivity, excellent separation efficiency, and high permeation flux. This review briefly discusses the fouling behavior of membranes and various basic wettability models. According to the special wettability, two major classes of membranes are discussed. One is superhydrophobic and superoleophilic; these membranes are selective for oil and reject water and are highly suitable for separating the water-in-oil emulsions. The second class of membranes is superhydrophilic and underwater superoleophobic; these membranes are highly selective for water, reject the oil, and are suitable for separating the oil-in-water emulsions. The properties and recent progress of the special wettable membranes are concisely discussed in each section. Finally, the review is closed with conclusive remarks and future directions.
... TiO 2 NPS was reported to significantly reduce fouling in PVDF-based membranes along with self-cleaning performance. The proposed green technology indicated its potential in liquid separation technology [180]. Further, a stable antifouling coating was constructed upon a PVDF membrane using a PVP-TiO 2 hydrophilic nanofiber membrane with a high flux recovery rate (FRR 95.68%) and a low total fouling ratio (15.18%) after several cycles [181]. ...
A greater interest has been observed in polymeric polyvinylidene fluoride (PVDF) nanofibers, emphasizing applications in the fields of energy generation (nanogenerators), water treatment (ultra-thin filtration membranes) and sensing technologies (wearable electronics). Coupled with intrinsic property traits such as flexible syntheses and wide-ranged dynamic versatility in user applications, research in polymeric material has intensified over the past decade. In literature, it was observed that the enhancement of the β-phase in PVDF crystals and fibers subsequently improved its electromechanical property. The advent of electrospinning technology provided effective control over the tuning of the β-phase. Thus, enabling functional integration and implementation into a wide variety of applications, particularly in aforementioned fields. Other significant applications of PVDF nanofibers include real-time health diagnostics, monitoring and self-powered bio-implants. This review aims to provide a commentary from a materials chemistry perspective with a focus on engineering the PVDF material into a suitable crystalline phase. Subsequently, its multifaceted utilization in a renewable and sustainable format in potential applications is discussed.
... The highly specific surface area serves many fiber network micropores, improving filtration performance and efficiency for oil-water separation. In particular, highly-defined surface nanofibers can be altered to enhance their functionality by using surface-active chemical compounds (94). ...
... In recent years, researchers have been working on various physical and chemical methods to improve the performance of nanofibrous membranes. The surface of PVDF and PAN nanofiber membranes can be hydrophilized by using alkaline treatment (94). Using alkaline treatment with the attachment of nanoparticles improved permeability and reduced fouling of these membranes. ...
Industrialization, production, consumption, and oil spill accidents have increased environmental and health problems. Recovery and reuse of waste oil are critical issues that we need to protect the environment. Various techniques have been used to treat oily wastewater. Still, many of them are time-consuming, cause secondary pollution, low efficiency, energy inefficient, occupy large spaces, and require experts to use. Membrane technology serves as a fast and efficient method for the remediation of oily wastewater. This chapter discusses the application of nanofiber membranes for oily wastewater treatment and its current developments. With their superior properties (high surface area, high porosity, superior mechanical, electrical, and chemical properties), nanofibers find a wide range of applications in many areas such as batteries and fuel cells, tissue engineering, blood vessels, filtration, nervous system, drug delivery, and military products. Compared with other nanofiber production techniques, electrospinning is one of the most commonly used methods which enables to design of unique architecture scaffolds at various densities, pore size, and porosity. Moreover, a wide range of polymers can be used in electrospinning technology. Nanofibers are alternative materials for separating oil/water mixtures and emulsions with their unique specific surface area, tight pore size, interconnected nanoscale pores, and highly porous structure.
... Pristine PVDF is naturally hydrophobic. PVDF may be converted into a hydrophilic membrane by modifying its surface using alkaline treatment [23,24]. It was found that PVDF membranes can be attacked and degraded upon exposure, even to a low concentration of NaOH (0.01 M) solution [25]. ...
Membrane fouling is one of the most significant issues to overcome in membrane-based technologies as it causes a decrease in the membrane flux and increases operational costs. This study investigates the effect of common chemical cleaning agents on polymeric nanofibrous membranes (PNM) prepared by polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polyamide 6 (PA6) nanofibers. Common alkaline and acid membrane cleaners were selected as the chemical cleaning agents. Membrane surface morphology was investigated. The PAN PNM were selected and fouled by engine oil and then cleaned by the different chemical cleaning agents at various ratios. The SEM results indicated that the use of chemical agents had some effects on the surface of the nanofibrous membranes. Moreover, alkaline cleaning of the fouled membrane using the Triton X 100 surfactant showed a two to five times higher flux recovery than without using a surfactant. Among the tested chemical agents, the highest flux recovery rate was obtained by a binary solution of 5% sodium hydroxide + Triton for alkaline cleaning, and an individual solution of 1% citric acid for acidic cleaning. The results presented here provide one of the first investigations into the chemical cleaning of nanofiber membranes.
... Chemical grafting of titanium oxide onto the surface of PVDF membranes was carried out in [96]. The order of operations for modifying PVDF membranes is shown in Scheme 2. At the first stage, the hollow fiber PVDF membrane was treated with an alkali solution to replace fluorine ions with hydroxide ions-the dehydrofluorination process. ...
... As a result, hollow fiber membranes with a superhydrophilic surface were obtained, capable of separating oil-water emulsions with almost 100% selectivity. Scheme 2. Scheme of the modification of a hollow fiber membrane from PVDF [96] and PVDF + PAN [97]. ...
... Polyvinylidene fluoride has a large number of -F groups, thanks to which it is possible to carry out chemical grafting-for example, by aminosilanes [101], alkylamines [99], and, through the defluorination stage, titanium oxide [96]. In addition, PVDF membranes are modified by applying hydrophilic layers, dopamine [105], cellulose [103], and polymer mixing [107]. ...
This review is devoted to the application of bulk synthetic polymers such as polysulfone (PSf), polyethersulfone (PES), polyacrylonitrile (PAN), and polyvinylidene fluoride (PVDF) for the separation of oil-water emulsions. Due to the high hydrophobicity of the presented polymers and their tendency to be contaminated with water-oil emulsions, methods for the hydrophilization of membranes based on them were analyzed: the mixing of polymers, the introduction of inorganic additives, and surface modification. In addition, membranes based on natural hydrophilic materials (cellulose and its derivatives) are given as a comparison.
... The production of nanofibers and mats by electrospinning technology allows the easy production of nanofiber mats from biobased, man-made polymers or polymer blends and by adding particles of ceramics, metals or metal oxides etc. [2][3][4][5]. New materials are promising for use in filtration, energy, biomedicine, electromagnetic shielding, neuromorphic computing, spintronics or energy storage [6][7][8][9][10]. Nanofibers with magnetic properties (MNFs) produced with electrospinning technology are currently attracting great interest from both academia and industry due to the development of new materials with magnetic and conducting properties [11]. ...
Electrospun magnetic nanofibers are promising for a variety of applications in biomedicine, energy storage, filtration or spintronics. The surface morphology of nanofiber mats plays an important role for defined application areas. In addition, the distribution of magnetic particles in nanofibers exerts an influence on the final properties of nanofiber mats. A simple method for the production of magnetic nanofiber mats by the addition of magnetic nanoparticles in an electrospinning polymer solution was used in this study. In this work, magnetic nanofibers (MNFs) were prepared by needle-free electrospinning technique from poly(acrylonitrile) (PAN) in the low-toxic solvent dimethy lsulfoxide (DMSO) and 20 wt% Fe3O4 at different parameter conditions such as PAN concentration, voltage and ultrasonic bath. The distribution of nanoparticles in the fiber matrix was investigated as well as the chemical and morphological properties of the resulting magnetic nanofibers. In addition, the surface morphology of magnetic nanofiber mats was studied by confocal laser scanning microscope (CLSM), scanning electron microscope (SEM), Fourier transform infrared microscope (FTIR) and ImageJ software, and distribution of Fe3O4 particles in the matrix was investigated by energy dispersive X-ray spectroscopy (EDX).
... Even functionalization with molecules is possible [7,8]. Depending on the material composition, such nanofiber mats can be used for various applications, such as biotechnology, biomedicine and tissue engineering [9][10][11], filters for fluids and gases [12][13][14], and energy harvesting and storage [15][16][17]. Most recent applications can be found in water purification, H 2 production, environmental protection [18][19][20][21], or as catalysts [22][23][24]. ...
Electrospinning can be used to produce nanofiber mats containing diverse nanoparticles for various purposes. Magnetic nanoparticles, such as magnetite (Fe3O4), can be introduced to produce magnetic nanofiber mats, e.g., for hyperthermia applications, but also for basic research of diluted magnetic systems. As the number of nanoparticles increases, however, the morphology and the mechanical properties of the nanofiber mats decrease, so that freestanding composite nanofiber mats with a high content of nanoparticles are hard to produce. Here we report on poly (acrylonitrile) (PAN) composite nanofiber mats, electrospun by a needle-based system, containing 50 wt% magnetite nanoparticles overall or in the shell of core–shell fibers, collected on a flat or a rotating collector. While the first nanofiber mats show an irregular morphology, the latter are quite regular and contain straight fibers without many beads or agglomerations. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) reveal agglomerations around the pure composite nanofibers and even, round core–shell fibers, the latter showing slightly increased fiber diameters. Energy dispersive X-ray spectroscopy (EDS) shows a regular distribution of the embedded magnetic nanoparticles. Dynamic mechanical analysis (DMA) reveals that mechanical properties are reduced as compared to nanofiber mats with smaller amounts of magnetic nanoparticles, but mats with 50 wt% magnetite are still freestanding.
