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(a) Vacuum filtration method; 64 (b) layer-by-layer self-assembly method (LBL); 88 (c) spin coating method; 53 (d) spraying method; 71 (e) dip coating method. 74
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Significant achievements have been made in the development of next-generation filtration and separation membranes using graphene materials; graphene-based membranes are promising in many areas, such as membrane separation, water desalination, proton conductors, and energy storage and conversion. In recent years, based on the excellent barrier and p...
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... Moreover, it can easily control the thickness of the membrane and has is environment friendly. Vacuum ltration requires the lm-forming material to be dispersed in the solvent uniformly, and then the lm-forming material be deposited on the substrate under vacuum ltration condition due to uxion function of solvent molecules. As shown in Fig. 7, Sun et al. 64 prepared GO/silver nanoparticle composite membrane by using vacuum ltration method, and cellulose acetate membrane was used as substrate. In addition, the thickness of the membrane was controlled by the volume of the liquid. Wang's group 65 also used this method to prepare GO membrane and they used nanober mats to ...
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... Becerril et al. 70 prepared GO membranes by the spin coating method; they used sufficient solution of GO to cover the substrate completely and settle the GO for 60 seconds. At last, GO membrane was obtained under the condition of spin coating at the speed of 500, 800, and 1600 53 also prepared GO membranes by the spin coating method shown in Fig. 7(c). They conrmed that compared with drop coating, the GO membranes obtained by spin coating are more uniform and have a higher ...
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... solvent can evaporate rapidly and avoid aggregation of the graphene-based material aer deposition of droplets onto the substrate. Pham et al. 71 sprayed a mixture of GO solution and hydrazine hydrate solution onto preheated quartz substrates by the spraying method and used nitrogen as the carrier gas for the spray gun system, as we can see in Fig. 7(d). The spraying rate was 3 mL min À1 and the distance between the tip of the nozzle and the substrate was 12 cm. The spraying method can be carried out on any substrate and can be easily operated without worrying about damage caused by transfer. This method can be used to prepare large-area membranes, but the uniformity of the membrane ...
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... had high selectivity, good recyclability and a good adsorption capacity, nearly 165 times its own weight. Lou et al. 74 used the dip coating method to prepare a GO membrane modied by silane with ceramic as the substrate. Silane modication improved adhesion between GO and ceramic substrate and hydrophilicity of membrane was improved, as shown in Fig. ...
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Citations
... In order to prevent these problems, it is important to use water treatment applications and to control the quality of natural, drinking, or artificial water sources and basins . Graphene-based membranes are one of the most important functional membrane materials and of great interest in water treatment applications, thanks to its excellent lattice structure anti-fouling and antimicrobial activities, and its contamination resistances [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]28,29,32,36,[53][54][55][56][57]. As an example of the antimicrobial effect of graphene, a bacterial cell can be damaged and inactivated by the sharp edges of graphene [55], or bacterial cell walls can gain an inhibitory effect by the reduced graphene oxide [54]. ...
... The reason for this preference is the mechanical, chemical, thermal and optical durability of the polymer medium [15,23,25,28,36,46]. Graphene oxide [16][17][18]20,23,24,29,32,36,58] and reduced graphene [12,13,22,26,43,54,59] are the main derivatives of graphene, and they carry a significant share of graphene properties. Oxidation can reduce the graphene's aggregation tendency, and oxide form of graphene has both hydrophobic (graphene portion) and hydrophilic (like -COOH carboxyl group, or -OH hydroxyl group) edges that are shown in Figure 1. ...
... Graphene, CNTs, metal oxides like TiO2 and ZnO, and polymers like PVDF, PTFE, PVA, PC, and PVC, and in partial combinations together, are all good candidates to be used as membrane materials [8,9,. Graphene nanocomposite membranes with nanoparticles like CNTs exhibit high specific surface areas and photo catalytic activities which have been explored in water treatment applications [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]28,29,32,36,[42][43][44][45][66][67][68]. Moreover, when the graphene material is doped with CNTs and metal oxide nanoparticles, the surface morphology can be improved, contaminant selectivity, water flux or contaminant removal properties can be improved [15][16][17]21,29,45]. ...
Graphene, a two-dimensional hexagonal honeycomb carbon structure, is widely used in membrane technologies thanks to its unique optical, electrical, mechanical, thermal, chemical and photoelectric properties. The light weight, mechanical strength, anti-bacterial effect, and pollution-adsorption properties of graphene membranes are valuable in water treatment studies. Incorporation of nanoparticles like carbon nanotubes (CNTs) and metal oxide into the graphene filtering nanocomposite membrane structure can provide an improved photocatalysis process in a water treatment system. With the rapid development of graphene nanocomposites and graphene nanocomposite membrane-based acoustically supported filtering systems, including CNTs and visible-light active metal oxide photocatalyst, it is necessary to develop the researches of sustainable and environmentally friendly applications that can lead to new and groundbreaking water treatment systems. In this review, characteristic properties of graphene and graphene nanocomposites are examined, various methods for the synthesis and dispersion processes of graphene, CNTs, metal oxide and polymer nanocomposites and membrane fabrication and characterization techniques are discussed in details with using literature reports and our laboratory experimental results. Recent membrane developments in water treatment applications and graphene-based membranes are reviewed, and the current challenges and future prospects of membrane technology are discussed.
... The presence of these functionals group provides GO with good hydrophilicity and tuneable properties that favour the synthesis of polymeric membrane especially in water treatment and purification related process [49]. The positive impact of GO in membrane fabrication process has received tremendous interest from the researchers globally and there are lots of available review papers discussing on the encouraging performance of GO in membrane technology [50][51][52][53][54][55][56][57][58]. These review papers discussed on the recent development of GO based membrane, morphology and structural properties, modification and performance strategies, applications and preparation of GO based membrane. ...
Nanohybrid based polymeric membranes technology for water purification and separation have grown over the years associated to its advancement in the past decades and remarkable impact to the membrane characteristics and performance is encouraging. In this chapter, the progress of the nanohybrid based polymeric membranes for water-based application was divided into two major sections namely membrane technology and nanohybrid polymeric membranes. The membrane technology discussed on the pressure driven membrane process, membrane configuration, membrane fabrication, membrane materials and types of membranes while the latter part discussed on graphene oxide based and non-graphene nanohybrid based polymeric membrane for water purification and separation.
... Spraying method includes the use of an airbrush to spray a solution containing the fillers to a preheated substrate, leaving membranes modified with the fillers after solvent evaporation (Cheng et al., 2017). The spray gun serves to disperse and form fine droplets of the spray solution. ...
The thermal transfer between individual body and the surroundings occurs by several paths such as radiation, evaporation, conduction, and convection. Thermal management is related with the heat transfer between the human body and the surroundings which aims to keep the body temperature in the comfort range either via preserving or emitting the body heat. The essential duty of clothing is to contribute to the thermal balance of the human body by regulating the heat and moisture transfer. In the case of poorly controlled body heat, health problems such as hyperthermia and heatstroke along with environmental problems due to higher energy consumption can occur. Recently, research has been focused on advanced textiles with novel approaches on materials synthesis and structure design which can provide thermal comfort together with energy-saving. This review article focuses on the innovative strategies basically on the passive textile models for improved thermal conductivity. We will discuss both the fabrication techniques and the inclusion of carbon-based and boron-based fillers to form nano-hybrid textile solutions which are used to improve the thermal conductivity of the materials.
... Though membrane-less MEC reduces the capital cost, other factors like pH and methanogens limit pure hydrogen production. Thus, researchers are now moving towards the production of (bio)hythane (a mixture of methane and hydrogen) from wastewater and its utilization in current natural gasoperated engines (Huang et al. 2017). ...
In the global economy, agriculture is the chief contributor in terms of biomass
production. At present, recycling and reprocessing of agriculture wastes for bio-fuel and
energy production has become a gradually significant development area, having greater
prospective. India is an agro-based economy which generates about 400 million tonnes of
agriculture/forest wastes. The technologies for successful conversion of agricultural
wastes provide a new venture for production of augmented products such as feed, fodder,
food, organic/bio-products and bio-fuel/energy. Ball milling and chemical activation
techniques are used for conversion of wastes like coconut husk, cocoa pod, calabash and
palm midrib for producing activated carbons. Such activated carbons are used in
superconductors and batteries. Processes like pyrolysis liquefaction, gasification,
combustion, and fermentation, has been used for conversion of agro-wastes into heat,
electricity, fuels, ethanol and methanol respectively. Circular economy approach could be
used for producing value added products by processing agro-wastes into bio-plastics, bio-
energy, bio-fertilizer and bio-chemicals. For instance, succinic acid and glucose are
produced from food/agro-wastes via fermentation. Bio-refinery systems are used for
recycling rice husks for producing synthetic lubricants. Molding, pulping and hydro-
separation methods are used for production of sound proof systems, absorbent materials,
thermal insulators and packaging materials by recycling sugarcane bagasse, kenaf fibers etc. In recent years, research focused on utilization and management of agricultural
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exploitation, climate management and providing social and economic benefits.In long
term, the refinement in agro-waste management systems could provide new insight in the
development of novel advantageous materials of industrial importance including people
from rural areas, research institutes on a cost-allocation basis consequently leading to a
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... In this technique, a film-forming material needs to be uniformly dispersed in the solvent and further deposited on the substrate under vacuum filtration condition to enable the flux of solvent molecules ( Figure 8). Although it is an easy operation, vacuum filtration possesses limitations regarding the production of large-area membranes [82]. ...
Porous hydrophobic ceramic membranes have been increasingly applied in advanced membrane-based separation processes such as Direct Contact Membrane Distillation (DCMD) due to their higher chemical and mechanical resistances. The development of novel ceramic membranes enhanced with porosity is based on conventional techniques such as extrusion and tape casting, and unique processing such as dry-wet spinning and vacuum filtration. The relationships between shaping and surface hydrophobization related to the membrane structure, properties and performance of the ceramic membrane applied to DCMD are explained in this work. The manufacturing technique influences the membrane characteristics, and consequently the permeability in DCMD. Recent research is focused on manufacturing high porous hollow fibre ceramic membranes by dry-wet spinning. In contrast to the grafting of alkylsilanes, the chemical vapour deposition process has been applied as an effective surface modifying technique to enhance membrane hydrophobicity. Ceramic membranes are mostly applied to desalination in DCMD and have been little researched concerning the unique properties they can offer, such as superhydrophobicity and use in a harsh environment. In addition to the review of manufacturing techniques, polymer-derived ceramic (PDC) is proposed as a one-step ceramic membrane processing route for DCMD. Although only a handful of works addressed the use of PDC membranes applied to DCMD, the great potential of these materials is forecast.
... More recently, attention has moved to nano-material-based membranes, often incorporating 1D 14,15 , or more relevant here, 2D materials such as graphene and graphene oxide (GO) [16][17][18][19][20][21][22] or even 2D polymers 23 , for use in OPEN www.nature.com/scientificreports/ filtration. ...
The development of low-cost ultrafiltration membranes with relatively high flow rate and selectivity is an important goal which could improve access to clean water in the developing world. Here we demonstrate a method to infuse mixtures of graphene nanosheets and Teflon nanoparticles into ultra-cheap glass fibre membranes. Annealing the resultant composites leads to coalescence of the Teflon, resulting in very stable membranes with significantly enhanced mechanical properties. In filtration tests, while adding ~ 10 wt% graphene/Teflon to the glass fibre membrane decreased the flow rate by × 100, the selectivity improved by × 10³ compared to the neat glass fibre membrane. This combination of selectively and flow rate was significantly better than any commercial membrane tested under similar circumstances. We found these membranes could remove > 99.99% of 25–250 nm diameter SiC nanoparticles dispersed in ethanol, transmitting only particles with diameters < 40 nm, performance which is superior to commercial alumina membranes. Field trials on dirty canal water showed these composite membranes to remove aluminium to a level × 10 below the EU limit for drinking water and reduce iron and bacteria contents to below detectable levels.
... Wet coating by solution processing is the most conventional method to coat pristine air filter media with anti-viral material (Nguyen et al., 2012;Lou et al., 2014;Hu et al., 2015;Zhong et al., 2015;Cheng et al., 2017). In this method, the filter media needs to be soaked in a solution with a large amount of dispersed anti-viral material. ...
... Graphene-based materials functionalized with carboxylate groups, hydroxyl groups, nanoparticles and polymers have been synthesized by various kinds of non-covalent interactions [21][22][23][24][25][26]. More significantly, controllable interlayer spacing of GBMs offers a straightforward approach to adjust ion transport and selective ion retention [27][28][29]. ...
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.
Due to their extraordinary prospective uses, particularly in the areas of oil–water separation, underwater superoleophobic materials have gained increasing attention. Thus, artificial nacre has become an attractive candidate for oil–water separation due to its superhydrophilicity and underwater superoleophobicity properties. Synthesized artificial nacre has successfully achieved a high mechanical strength that is close to or even surpasses the mechanical strength of natural nacre. This can be attributed to suitable synthesis methods, the selection of inorganic fillers and polymer matrices, and the enhancement of the mechanical properties through cross-linking, covalent group modification, or mineralization. The utilization of nacre-inspired composite membranes for emerging applications, i.e., is oily wastewater treatment, is highlighted in this review. The membranes show that full separation of oil and water can be achieved, which enables their applications in seawater environments. The self-cleaning mechanism’s basic functioning and antifouling tips are also concluded in this review.
Plate-like sheet networks assembled by randomly distributed sheets are commonly found in artificial nacre-like materials. However, the effects of spatial randomness and porosity of the network on its mechanical properties still remain largely unrevealed. To make a comprehensive understanding on the elasticity of these networks, a mechanics model is established based on the effective medium method where the intralayer spatial randomness of the sheets and porosity of the network are considered. An analytical expression of the effective Young’s modulus of random sheet networks is derived and verified by FE simulation. The effective elastic modulus of the network is a quadratic function of the effective sheet area fraction that can be obtained by the real sheet area fraction minus a threshold. The threshold is ineffective sheet area fraction that cannot contribute to load bearing, and found to be a constant as 0.25. Besides, the effects of sheet size dispersion and sheet shape on the effective Young’s modulus are investigated. The modulus can be improved by increasing the diameter variance or replacing the circular sheets with square sheets. This work provides a method to estimate the effect of randomness of arrangement, size and shape of sheets on the elasticity of network materials.
