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Polymer membranes reinforced with carbon-based nanomaterials for water purification
Polymer membranes reinforced with carbon-based nanomaterials for water purification
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Runcy Wilson*, Gejo George†, Ajith J. Jose† *Mahatma Gandhi University, Kottayam, India, †St. Berchmans College (Autonomous), Changanassery, India
1
Introduction
The past few decades have witnessed a growing need for fresh water, owing to the sharp growth in the world’s human population [1,2]. It has recently been estimated that more than 1.2 billion people in the world lack access to clean and safe drinking water, and it is expected to grow worse in the coming years [2,3]. Growing industrialization and urbanization worldwide has led to the decrease in safe drinking water resources available to humans, which is one of the most important worldwide problems [1,4]. A large number of people have become sick or died as a result of the growing contamination of water, or the unavailability of safe drinking water [4]. The most commonly used water purification techniques (drinking and wastewater treatment, desalination, etc.) involve membrane processes such as reverse osmosis, nanofiltration, ultrafiltration, microfiltration, membrane distillation, pervoparation, etc. [2,5]. The currently used membranes are mostly polymeric in nature; however, these polymeric membranes have several disadvantages, including fouling, chemical and thermal stability, etc. [2,6,7]. Enhancements to improve their performance in terms of water flux, salt rejection, and resistance to a foul smell are the major obstacles in membrane-assisted desalination technologies. Recently a prospect to associate nanotechnology with polymeric RO membrane improvement was proposed, owing to the growing evolution of nanotechnology in the past few years. Several researchers have already successfully reported the incorporation of carbon nanotubes, graphene, and zeolites into RO membranes at the laboratory scale [6]. However, the major challenges related to nanoparticle incorporation into membranes are scaling up and its practical use. The current state of water purification membrane research has forced researchers to search for novel membranes to improve their performance, properties, and water purification efficiency [8]. The new membranes must be designed in such a way that they should specifically target water treatment applications by fine tuning structural and chemical properties (which may include hydrophilicity, porosity, membrane charge, thermal stability, etc.). In addition, the researchers can also try to add antibacterial, photocatalytic, or adsorption ability functionalities to the novel membrane [2]. New Polymer Nanocomposites for Environmental Remediation. https://doi.org/10.1016/B978-0-12-811033-1.00018-4 © 2018 Elsevier Inc. All rights reserved.
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A growing interest in using nanomaterials for the fabrication of novel membranes equipped with advanced properties has been noted during the past few years [8]. Among the various nanomaterials currently being researched, carbon-based nanomaterials are the most promising contenders to tackle this challenge, owing to their exceptional mechanical, chemical, and thermal stability and conductive and antibacterial properties [7,9–11]. This chapter describes the current state of carbonbased nanomaterials for water purification applications.
2
Carbon-based nanomaterials and their general characteristics
The most common carbon-based nanomaterials include fullerenes, carbon nanotubes (CNT), carbon nanofiber (CNF), pristine graphene, graphene oxide (GO), and MXene etc (Fig. 1). They have distinctive characteristics such as high chemical, thermal, and mechanical strength, excellent conductivity (both thermal and electrical), optical properties, and low density [2]. A sheet of carbon atoms that are rolled into hollow, smooth cylindrical tubes make up carbon nanotubes. Single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) are the two variations of CNT available that differ in the number of carbon atom cylindrical arrays arranged around the hollow nanotube core [2,12]. They have characteristic structural and functional properties such as high mechanical strength and conductivity along with a high aspect ratio [13–15]. Graphene is another carbon-based nanomaterial, researched extensively in various applications during the past few years [9,16–19]. Graphene is an allotrope of carbon in the form of a two-dimensional honeycomb lattice in which one carbon atom forms each vertex. Graphene has several characteristic properties, such as being lightweight, and having high thermal and electrical conductivities, etc. [20,21]. Graphene oxide (GO) is obtained by oxidizing graphene with strong acids or oxidizers and, in general, GO is a reformed version of graphene with oxygen and hydrogen atoms being bonded to carbon atoms [16]. GO disperses well in water and other organic solvents because of the presence of oxygen and hydrogen-based functional groups which in turn would facilitate the preparation of GO-based membranes [17]. A single graphite layer or double graphite layers stacked parallel or at a specific angle from the fiber axis are carbon nanofibers [22,23]. Carbon nanofibers have different structures, including parallel, cup-stacked, and herringbone-like structures [24]. Fullerene has a hollow structure that takes the shape of a sphere, tube, or ellipsoid, and in general is an allotrope of carbon [25]. Bucky Balls are spherical fullerenes that look like balls. Structurally, fullerenes are similar to graphite and consist of arranged graphene sheets [25]. The past few years have witnessed considerable use of carbon nanomaterials (CNMs) in membrane fabrication and modification owing to CNMs valuable properties [17]. Liu et al. [26] reported that CNTs, graphene, and GO inhibit the growth of bacteria when they are in direct contact with bacterial cells. In has been reported that the hydrophilicity, flux, and rejection of the prepared membranes increased as a result
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Fig. 1 (A) Schematic representation of fullerene, carbon nanotube and graphene, (B) SEM image of carbon nanotube, (C and D) TEM image of carbon nanotube, (E) TEM image of graphene array, (F) graphene oxide structure, (G) representation of carbon nanofibers, (H) SEM image of carbon nanofiber, (I) SEM of MXene, and (J)TEM of fullerene. Reproduced with permission from Y. Manawi, V. Kochkodan, M.A. Hussein, M.A. Khaleel, M. Khraisheh, N. Hilal, Can carbon-based nanomaterials revolutionize membrane fabrication for water treatment and desalination? Desalination 391 (2016) 69–88.
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of embedding hydrophilic carbon nanomaterials in membrane synthesis [27,28]. Membrane properties such as hydrophilicity, flux, rejection, and chemical, thermal, and mechanical stability can be fine-tuned by incorporating CNMs in the membrane preparation process, and also could introduce additional membrane properties such as antibacterial, photocatalytic, and conductive properties [26]. Hence, various CNMs are currently widely studied by research groups in efforts to manufacture membranes with advanced properties for water treatment.
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Polymer membranes reinforced with carbon-based nanomaterials for water purification
Choi et al. [29] reported that the coating of GO nanosheets on the surface of fully aromatic PA-TFC membranes serves as a dual-functional protective layer to improve both membrane antifouling and chlorine resistance, while maintaining its separation performance. Choi et al. [29] deposited GO multilayers on the membrane surface using an LbL technique, which is a simple, but reliable process for producing conformal GO assembly in a controllable manner. Fig. 2 shows a schematic representation of LbL deposition of AGO and GO nanosheets on the PA-TFC membrane surface. In order to study the effect of GO coating on membrane properties, the salt rejection and water flux of GO-coated and uncoated PA membranes were studied as a function of thickness of GO bi-layers on the PA membrane (Fig. 3).
Fig. 2 Schematic representation of LbL deposition of AGO and GO nanosheets on the PA-TFC membrane surface. Reproduced with permission from W. Choi, J. Choi, J. Bang, J.-H. Lee, Layer-by-layer assembly of graphene oxide nanosheets on polyamide membranes for durable reverse-osmosis applications, ACS Appl. Mat. Inter. 5 (2013) 12510–12519.
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Fig. 3 The water flux and NaCl (salt) rejection properties of GO-coated PA membranes as a function of GO layer thickness where 0 denotes the pristine PA membrane without any GO coating. Reproduced with permission from W. Choi, J. Choi, J. Bang, J.-H. Lee, Layer-by-layer assembly of graphene oxide nanosheets on polyamide membranes for durable reverse-osmosis applications, ACS Appl. Mat. Inter. 5 (2013) 12510–12519.
Choi et al. [29] reported that in their study, they found out that after the modification of the membrane with GO coating, the performance remained basically unchanged; however, within measurement errors, regardless of the number of GO bilayers on the PA membrane surface. As per Choi et al. [29], this result was quite intriguing because usually one would expect that the GO surface coating would reduce the water flux, because upon applying the GO coating on the PA membrane surface, it will become smoother, thereby resulting in a decreased effective contact area and increased hydrodynamic resistance. Choi et al. [29] attributed this unique phenomenon, in all probability, to the unique water transport (frictionless and super fast) through the stacked GO nanosheets [16]. Choi et al. [29] concluded that they successfully developed a dual-action robust coating strategy to improve the fouling and chlorine-induced degradation resistance of PA membranes via a layer-by-layer (LbL) deposition technique of graphene oxide (GO) nanosheets onto the PA membrane. The membranes fabricated by Choi et al. [29] were reported to have good membrane permeability compared with conventional coatings, where normally a flux decline is noticed. This was reported by Choi et al. [29] to be due to the unique water transport mechanism between GO nanosheets. Sun et al. [4] successfully verified water purification and ion penetration (which is rather selective) properties/characteristics of freestanding graphene oxide (GO) membranes. Membranes reinforced with freestanding GO were fabricated by Sun et al. [4] using a simple drop-casting method. The ion penetration studies of the prepared GO membranes were done using a homemade plastic sink that was separated by a plastic plate (Fig. 4). Sun et al. [4] concluded that the sodium salts permeated very quickly through the GO membranes; however, heavy metal salts permeated much more slowly compared with sodium salts. Sodium salts permeated through GO membranes quickly, whereas heavymetal salts infiltrated much more slowly. A rather interesting result was observed in the case of copper salts; they were entirely blocked by the GO membranes along with organic contaminants. Sun et al. [4] reported that salts such as copper sulfate and organic contaminants such as rhodamine B were entirely blocked by the GO membrane, owing
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Fig. 4 A schematic representation of the ion penetration technique used by Sun et al. [4] and penetration behavior of different ions through GO membranes. Reproduced with permission from P. Sun, M. Zhu, K. Wang, M. Zhong, J. Wei, D. Wu, Z. Xu, H. Zhu, Selective ion penetration of graphene oxide membranes, ACS Nano 7 (2013) 428–437.
to their strong interactions with the GO membrane. According to Sun et al., [4] graphene-derivative incorporated polymer membranes have a promising future in the field of barrier and wastewater purification technologies. Baek et al. [30] reported the successful fabrication of vertically aligned carbon nanotube (VA CNT) membranes, and claim it to be the next-generation membrane due to its fast water transport and antimicrobial properties. The vertically aligned carbon nanotube membrane was synthesized onto a Si wafer from a Fe catalyst using the waterassisted thermal chemical vapor deposition method by Baek et al. [30]. The schematic representation of the membrane fabrication and its casting is shown as Fig. 5. Fig. 6 shows the water flux of the VACNT membrane with its enhancement factor compared with that of the commercially available UF membrane [30]. Baek et al. [30] report that the VACNT membrane showed water flux that was about three times faster than the commercially available UF membrane. However, as per Baek et al. [30], it should be clearly noted that the VACNT membrane achieved this high water flux even with its smaller pore diameter, lower pore density, and thickness that was approximately 2000 times more. Baek et al. [30] also reported that the produced VACNT membrane showed better biofouling resistance than the conventional commercially available UF membrane, by approximately 15% less permeate flux reduction and 2 logs of less bacterial attachment compared with that of the UF membrane. Recently Dai et al. [31] reported the use of multi-walled carbon nanotubes to improve the performance of laccase-carrying electrospun fibrous membranes (LCEFMs). The authors used the technique of electrospinning to fabricate the laccase-carrying electrospun fibrous membranes (LCEFMs). The authors reported 90% removal efficiency of the pollutant bisphenol A from water using MWCNTsLCEFMs. The morphologies of MWCNTs-LCEFMs modified by MWCNTs (1.5 wt%) were characterized by SEM (under different resolutions), and the images are shown in Fig. 7. The authors reported the fabrication of bead-free, continuous, and randomly arrayed linear fibers of MWCNTs-LCEFMs [31]. Based on previous reports, the authors also concluded that the addition of MWCNTs could augment the conductivity of the spinning solution, thus leading to a decrease of the fiber
Fig. 5 Schematic representation of vertically aligned carbon nanotube membrane fabrication; (A) transfer of VACNTs to the tape, (B) infiltration of epoxy into the vacant areas of VACNTs utilizing the cast, and (C) fabrication of the VACNT membrane utilizing microtome. Reproduced with permission from Y. Baek, C. Kim, D.K. Seo, T. Kim, J.S. Lee, Y.H. Kim, K.H. Ahn, S.S. Bae, S.C. Lee, J. Lim, K. Lee, J. Yoon, High performance and antifouling vertically aligned carbon nanotube membrane for water purification, J. Membr. Sci. 460 (2014) 171–177. 1e+7 Water flux Enhancement factor
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Fig. 6 Water flux of the VACNT membrane with its enhancement factor compared with that of the commercially available UF membrane. Reproduced with permission from Y. Baek, C. Kim, D.K. Seo, T. Kim, J.S. Lee, Y.H. Kim, K.H. Ahn, S.S. Bae, S.C. Lee, J. Lim, K. Lee, J. Yoon, High performance and antifouling vertically aligned carbon nanotube membrane for water purification, J. Membr. Sci. 460 (2014) 171–177.
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(A)
(B)
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Fig. 7 SEM micrographs of multi-walled carbon nanotubes modified laccase-carrying electrospun fibrous membranes (1.5 wt%) (MWCNTs-LCEFMs) under different resolutions: (A) 10,000; (B) 50,000; (C) 1,00,000; and (D) MWCNTs-LCEFMs with 2 wt% MWCNT loading. Reproduced with permission from Y. Dai, J. Yao, Y. Song, X. Liu, S. Wang, Y. Yuan, Enhanced performance of immobilized laccase in electrospun fibrous membranes by carbon nanotubes modification and its application for bisphenol A removal from water, J. Haz. Mat. 317 (2016) 485–493.
diameter [31–33]. The authors, however, concluded that on continuing to increase the MWCNT’s dosage in the membrane to 2.0 wt%, some beads started to appear on the fiber surface; however, the fibrous diameter was still fine [31]. According to Dai et al. [31], the fabricated MWCNTs-LCEFMs could efficiently (above 90% as shown in Fig. 8) remove the contaminant Bisphenol A from water over a wide range of pH and temperatures, indicating their excellent potential for the treatment of Bisphenol A-contaminated wastewater. Yoon et al. [34] reported the fabrication of a simple, low-cost membrane suitable for gravity-driven oil-water separation and water purification using aqueous poly(diallyldimethylammonium chloride) solution, sodium perfluorooctanoate, silica nanoparticles, and a graphene plug stacked below the membrane to remove watersoluble organics by adsorption. Yoon et al. [34] fabricated the oil water separator assembly by simply dip coating a stainless steel mesh with the abovementioned mixture (Fig. 9).
Polymer membranes reinforced with carbon-based nanomaterials for water purification 100 0.5 wt% 1.5 wt%
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Fig. 8 The (A) adsorption and (B) removal characteristics of bisphenol A from contaminated wastewater by multi-walled carbon nanotubes modified laccase-carrying electrospun fibrous membranes (MWCNTs-LCEFMs) with varying concentrations of MWCNTs. Reproduced with permission from Y. Dai, J. Yao, Y. Song, X. Liu, S. Wang, Y. Yuan, Enhanced performance of immobilized laccase in electrospun fibrous membranes by carbon nanotubes modification and its application for bisphenol A removal from water, J. Haz. Mat. 317 (2016) 485–493.
Oil MB solution Hybrid filter
I : Composite membrane
II : Graphene plug
Purified water
Fig. 9 The oil water separator assembly fabricated by Yoon et al. [34]. Reproduced with permission from H. Yoon, S.-H. Na, J.-Y. Choi, S.S. Latthe, M.T. Swihart, S.S. Al-Deyab, S.S. Yoon, Gravity-driven hybrid membrane for oleophobic super hydrophilic oil water separation and water purification by graphene, Langmuir 30 (2014) 11761–11769.
Yoon et al. [34] used methylene blue as the contaminant to demonstrate the efficiency of their model. The biggest advantage of this technique is its simplicity and ability to be scaled up for mass production. Using the abovementioned model, water was quickly and selectively removed from oil by the composite membrane, which also had the additional capacity for water purification using the graphene plug in the system.
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Fig. 10 Schematics of oil-methylene blue (MB) separation capability as well as purification of MB by composite membrane containing a graphene plug. Reproduced with permission from H. Yoon, S.-H. Na, J.-Y. Choi, S.S. Latthe, M.T. Swihart, S.S. Al-Deyab, S.S. Yoon, Gravity-driven hybrid membrane for oleophobic superhydrophilic oil water separation and water purification by graphene, Langmuir 30 (2014) 11761–11769.
In order to prove that their model is efficient for oil-water separation and wastewater purification, Yoon et al. [34] performed another experiment in which a graphene plug was stacked below the composite membrane. Yoon et al. [34] reported that this assembly could efficiently separate hexadecane from an aqueous solution containing methylene blue and also completely decolor the methylene blue solution, indicating its removal from the aqueous media (Fig. 10).
4
Conclusions
Membrane technology is established as one of the competitive treatments in the field of water purification when compared with conventional ones. The combination of various methods, along with polymer nanocomposites membranes, is very useful for removal of contaminants. Several studies have shown that carbon-reinforced polymer membranes act as a good pretreatment method of the raw water. Recent advances in the nanotechnology suggest that many of the issues involving water quality could be resolved, or greatly ameliorated, using carbon-reinforced polymeric membranes. Innovations in the development of novel technologies to desalinate water are among the most exciting and promising. Utilization of nanoparticles either embedded in membranes or on other structural media that can effectively, inexpensively, and rapidly render unusable water potable is being explored at a variety of institutions. In addition to obvious advantages for industrialized nations, the benefits for developing countries would also be enormous.
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References [1] M.A. Shannon, P.W. Bohn, M. Elimelech, J.G. Georgiadis, B.J. Marinas, A.M. Mayes, Science and technology for water purification in the coming decades, Nature 452 (2008) 301–310. [2] Y. Manawi, V. Kochkodan, M.A. Hussein, M.A. Khaleel, M. Khraisheh, N. Hilal, Can carbon-based nanomaterials revolutionize membrane fabrication for water treatment and desalination? Desalination 391 (2016) 69–88. [3] M.A. Montgomery, M. Elimelech, Water and sanitation in developing countries: including health in the equation, Environ. Sci. Technol. 41 (2007) 17–24. [4] P. Sun, M. Zhu, K. Wang, M. Zhong, J. Wei, D. Wu, Z. Xu, H. Zhu, Selective ion penetration of graphene oxide membranes, ACS Nano 7 (2013) 428–437. [5] M. Elimelech, W.A. Phillip, The future of seawater desalination: energy, technology, and the environment, Science 333 (2011) 712–717. [6] K.P. Lee, T.C. Arnot, D. Mattia, A review of reverse osmosis membrane materials for desalination—development to date and future potential, J. Membr. Sci. 370 (2011) 1–22. [7] H. El-Saied, A.H. Basta, B.N. Barsoum, M.M. Elberry, Cellulose membranes for reverse osmosis part I. RO cellulose acetate membranes including a compositewith polypropylene, Desalination 159 (2003) 171–181. [8] V. Kochkodan, N. Hilal, A comprehensive review on surface modified polymer membranes for biofouling mitigation, Desalination 356 (2015) 187–207. [9] S. Daer, J. Kharraz, A. Giwa, S.W. Hasan, Recent applications of nanomaterials inwater desalination: a critical review and future opportunities, Desalination 367 (2015) 37–48. [10] X. Song, L. Wang, C.Y. Tang, Z. Wang, C. Gao, Fabrication of carbon nanotubes incorporated double-skinned thin film nanocomposite membranes for enhanced separation performance and antifouling capability in forward osmosis process, Desalination 369 (2015) 1–9. [11] M. Tian, R. Wang, K. Goh, Y. Liao, A.G. Fane, Synthesis and characterization of high performance novel thin film nanocomposite PRO membranes with tiered nanofiber support reinforced by functionalized carbon nanotubes, J. Membr. Sci. 486 (2015) 151–160. [12] K. Balasubramanian, M. Burghard, Chemically functionalized carbon nanotubes, Small 1 (2005) 180–192. [13] W. Hoenlein, F. Kreupl, G. Duesberg, A. Graham, M. Liebau, R. Seidel, E. Unger, Carbon nanotubes for microelectronics: status and future prospects, Mater. Sci. Eng. C 23 (2003) 663–669. [14] S. Beg, M. Rizwan, A.M. Sheikh, M.S. Hasnain, K. Anwer, K. Kohli, Advancement in carbon nanotubes: basics, biomedical applications and toxicity, J. Pharm. Pharmacol. 63 (2011) 141–163. [15] M. Cadek, J. Coleman, V. Barron, K. Hedicke, W. Blau, Morphological and mechanical properties of carbon-nanotube-reinforced semicrystalline and amorphous polymer composites, Appl. Phys. Lett. 81 (2002) 5123–5125. [16] M. Hu, B. Mi, Enabling graphene oxide nanosheets as water separation membranes, Environ. Sci. Technol. 47 (2013) 3715–3723. [17] S. Stankovich, D.A. Dikin, R.D. Piner, K.A. Kohlhaas, A. Kleinhammes, Y. Jia, Y. Wu, S. T. Nguyen, R.S. Ruoff, Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide, Carbon 45 (2007) 1558–1565. [18] F. Perreault, M.E. Tousley, M. Elimelech, Thin-film composite polyamide membranes functionalized with biocidal graphene oxide nanosheets, Environ. Sci. Technol. Lett. 1 (2014) 71–76.
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[19] B.M. Ganesh, A.M. Isloor, A.F. Ismail, Enhanced hydrophilicity and salt rejection study of graphene oxide-polysulfone mixed matrix membrane, Desalination 313 (2013) 199–207. [20] A.A. Balandin, S. Ghosh, W. Bao, I. Calizo, D. Teweldebrhan, F. Miao, C.N. Lau, Superior thermal conductivity of single-layer graphene, Nano Lett. 8 (2008) 902–907. [21] B. Marinho, M. Ghislandi, E. Tkalya, C.E. Koning, G. deWith, Electrical conductivity of compacts of graphene, multi-wall carbon nanotubes, carbon black, and graphitepowder, Powder Technol. 221 (2012) 351–358. [22] M.H. Al-Saleh, U. Sundararaj, A review of vapor grown carbon nanofiber/polymer conductive composites, Carbon 47 (2009) 2–22. [23] H. Miyagawa, M.J. Rich, L.T. Drzal, Thermo-physical properties of epoxy nanocomposites reinforced by carbon nanotubes and vapor grown carbon fibers, Thermochim. Acta 442 (2006) 67–73. [24] M. Endo, Y. Kim, T. Hayashi, K. Nishimura, T. Matusita, K. Miyashita, M. Dresselhaus, Vapor-grown carbon fibers (VGCFs): basic properties and their battery applications, Carbon 39 (2001) 1287–1297. [25] B. Yadav, R. Kumar, Structure, properties and applications of fullerenes, Int. J. Nanotechnol. Appl. 2 (2008) 15–24. [26] S. Liu, T.H. Zeng, M. Hofmann, E. Burcombe, J. Wei, R. Jiang, J. Kong, Y. Chen, Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: membrane and oxidative stress, ACS Nano 5 (2011) 6971–6980. [27] L. Zhang, G.-Z. Shi, S. Qiu, L.-H. Cheng, H.-L. Chen, Preparation of high-flux thin film nanocomposite reverse osmosis membranes by incorporating functionalized multi-walled carbon nanotubes, Desalin. Water Treat. 34 (2011) 19–24. [28] P. Daraei, S.S. Madaeni, N. Ghaemi, M.A. Khadivi, B. Astinchap, R. Moradian, Enhancing antifouling capability of PES membrane via mixing with various types of polymer modified multi-walled carbon nanotube, J. Membr. Sci. 444 (2013) 184–191. [29] W. Choi, J. Choi, J. Bang, J.-H. Lee, Layer-by-layer assembly of graphene oxide nanosheets on polyamide membranes for durable reverse-osmosis applications, ACS Appl. Mater. Interfaces 5 (2013) 12510–12519. [30] Y. Baek, C. Kim, D.K. Seo, T. Kim, J.S. Lee, Y.H. Kim, K.H. Ahn, S.S. Bae, S.C. Lee, J. Lim, K. Lee, J. Yoon, High performance and antifouling vertically aligned carbon nanotube membrane for water purification, J. Membr. Sci. 460 (2014) 171–177. [31] Y. Dai, J. Yao, Y. Song, X. Liu, S. Wang, Y. Yuan, Enhanced performance of immobilized laccase in electrospun fibrous membranes by carbon nanotubes modification and its application for bisphenol A removal from water, J. Hazard. Mater. 317 (2016) 485–493. [32] J. Quan, Z. Liu, C. Branford-White, H. Nie, L. Zhu, Fabrication of glycopolymer/ MWCNTs composite nanofibers and its enzyme immobilization applications, Colloids Surf. B 121 (2014) 417–424. [33] E. Sapountzi, M. Braiek, C. Farre, M. Arab, J.F. Chateaux, N. Jaffrezic-Renault, F. Lagarde, One-step fabrication of electrospun photo-cross-linkable polymer nanofibers incorporating multiwall carbon nanotubes and enzyme for biosensing, J. Electrochem. Soc. 162 (2015) B275–B281. [34] H. Yoon, S.-H. Na, J.-Y. Choi, S.S. Latthe, M.T. Swihart, S.S. Al-Deyab, S.S. Yoon, Gravity-driven hybrid membrane for oleophobic super hydrophilic oil water separation and water purification by graphene, Langmuir 30 (2014) 11761–11769.
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Runcy Wilson*, Gejo George†, Ajith J. Jose† *Mahatma Gandhi University, Kottayam, India, †St. Berchmans College (Autonomous), Changanassery, India
1
Introduction
The past few decades have witnessed a growing need for fresh water, owing to the sharp growth in the world’s human population [1,2]. It has recently been estimated that more than 1.2 billion people in the world lack access to clean and safe drinking water, and it is expected to grow worse in the coming years [2,3]. Growing industrialization and urbanization worldwide has led to the decrease in safe drinking water resources available to humans, which is one of the most important worldwide problems [1,4]. A large number of people have become sick or died as a result of the growing contamination of water, or the unavailability of safe drinking water [4]. The most commonly used water purification techniques (drinking and wastewater treatment, desalination, etc.) involve membrane processes such as reverse osmosis, nanofiltration, ultrafiltration, microfiltration, membrane distillation, pervoparation, etc. [2,5]. The currently used membranes are mostly polymeric in nature; however, these polymeric membranes have several disadvantages, including fouling, chemical and thermal stability, etc. [2,6,7]. Enhancements to improve their performance in terms of water flux, salt rejection, and resistance to a foul smell are the major obstacles in membrane-assisted desalination technologies. Recently a prospect to associate nanotechnology with polymeric RO membrane improvement was proposed, owing to the growing evolution of nanotechnology in the past few years. Several researchers have already successfully reported the incorporation of carbon nanotubes, graphene, and zeolites into RO membranes at the laboratory scale [6]. However, the major challenges related to nanoparticle incorporation into membranes are scaling up and its practical use. The current state of water purification membrane research has forced researchers to search for novel membranes to improve their performance, properties, and water purification efficiency [8]. The new membranes must be designed in such a way that they should specifically target water treatment applications by fine tuning structural and chemical properties (which may include hydrophilicity, porosity, membrane charge, thermal stability, etc.). In addition, the researchers can also try to add antibacterial, photocatalytic, or adsorption ability functionalities to the novel membrane [2]. New Polymer Nanocomposites for Environmental Remediation. https://doi.org/10.1016/B978-0-12-811033-1.00018-4 © 2018 Elsevier Inc. All rights reserved.
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A growing interest in using nanomaterials for the fabrication of novel membranes equipped with advanced properties has been noted during the past few years [8]. Among the various nanomaterials currently being researched, carbon-based nanomaterials are the most promising contenders to tackle this challenge, owing to their exceptional mechanical, chemical, and thermal stability and conductive and antibacterial properties [7,9–11]. This chapter describes the current state of carbonbased nanomaterials for water purification applications.
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Carbon-based nanomaterials and their general characteristics
The most common carbon-based nanomaterials include fullerenes, carbon nanotubes (CNT), carbon nanofiber (CNF), pristine graphene, graphene oxide (GO), and MXene etc (Fig. 1). They have distinctive characteristics such as high chemical, thermal, and mechanical strength, excellent conductivity (both thermal and electrical), optical properties, and low density [2]. A sheet of carbon atoms that are rolled into hollow, smooth cylindrical tubes make up carbon nanotubes. Single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) are the two variations of CNT available that differ in the number of carbon atom cylindrical arrays arranged around the hollow nanotube core [2,12]. They have characteristic structural and functional properties such as high mechanical strength and conductivity along with a high aspect ratio [13–15]. Graphene is another carbon-based nanomaterial, researched extensively in various applications during the past few years [9,16–19]. Graphene is an allotrope of carbon in the form of a two-dimensional honeycomb lattice in which one carbon atom forms each vertex. Graphene has several characteristic properties, such as being lightweight, and having high thermal and electrical conductivities, etc. [20,21]. Graphene oxide (GO) is obtained by oxidizing graphene with strong acids or oxidizers and, in general, GO is a reformed version of graphene with oxygen and hydrogen atoms being bonded to carbon atoms [16]. GO disperses well in water and other organic solvents because of the presence of oxygen and hydrogen-based functional groups which in turn would facilitate the preparation of GO-based membranes [17]. A single graphite layer or double graphite layers stacked parallel or at a specific angle from the fiber axis are carbon nanofibers [22,23]. Carbon nanofibers have different structures, including parallel, cup-stacked, and herringbone-like structures [24]. Fullerene has a hollow structure that takes the shape of a sphere, tube, or ellipsoid, and in general is an allotrope of carbon [25]. Bucky Balls are spherical fullerenes that look like balls. Structurally, fullerenes are similar to graphite and consist of arranged graphene sheets [25]. The past few years have witnessed considerable use of carbon nanomaterials (CNMs) in membrane fabrication and modification owing to CNMs valuable properties [17]. Liu et al. [26] reported that CNTs, graphene, and GO inhibit the growth of bacteria when they are in direct contact with bacterial cells. In has been reported that the hydrophilicity, flux, and rejection of the prepared membranes increased as a result
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Fig. 1 (A) Schematic representation of fullerene, carbon nanotube and graphene, (B) SEM image of carbon nanotube, (C and D) TEM image of carbon nanotube, (E) TEM image of graphene array, (F) graphene oxide structure, (G) representation of carbon nanofibers, (H) SEM image of carbon nanofiber, (I) SEM of MXene, and (J)TEM of fullerene. Reproduced with permission from Y. Manawi, V. Kochkodan, M.A. Hussein, M.A. Khaleel, M. Khraisheh, N. Hilal, Can carbon-based nanomaterials revolutionize membrane fabrication for water treatment and desalination? Desalination 391 (2016) 69–88.
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of embedding hydrophilic carbon nanomaterials in membrane synthesis [27,28]. Membrane properties such as hydrophilicity, flux, rejection, and chemical, thermal, and mechanical stability can be fine-tuned by incorporating CNMs in the membrane preparation process, and also could introduce additional membrane properties such as antibacterial, photocatalytic, and conductive properties [26]. Hence, various CNMs are currently widely studied by research groups in efforts to manufacture membranes with advanced properties for water treatment.
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Polymer membranes reinforced with carbon-based nanomaterials for water purification
Choi et al. [29] reported that the coating of GO nanosheets on the surface of fully aromatic PA-TFC membranes serves as a dual-functional protective layer to improve both membrane antifouling and chlorine resistance, while maintaining its separation performance. Choi et al. [29] deposited GO multilayers on the membrane surface using an LbL technique, which is a simple, but reliable process for producing conformal GO assembly in a controllable manner. Fig. 2 shows a schematic representation of LbL deposition of AGO and GO nanosheets on the PA-TFC membrane surface. In order to study the effect of GO coating on membrane properties, the salt rejection and water flux of GO-coated and uncoated PA membranes were studied as a function of thickness of GO bi-layers on the PA membrane (Fig. 3).
Fig. 2 Schematic representation of LbL deposition of AGO and GO nanosheets on the PA-TFC membrane surface. Reproduced with permission from W. Choi, J. Choi, J. Bang, J.-H. Lee, Layer-by-layer assembly of graphene oxide nanosheets on polyamide membranes for durable reverse-osmosis applications, ACS Appl. Mat. Inter. 5 (2013) 12510–12519.
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Fig. 3 The water flux and NaCl (salt) rejection properties of GO-coated PA membranes as a function of GO layer thickness where 0 denotes the pristine PA membrane without any GO coating. Reproduced with permission from W. Choi, J. Choi, J. Bang, J.-H. Lee, Layer-by-layer assembly of graphene oxide nanosheets on polyamide membranes for durable reverse-osmosis applications, ACS Appl. Mat. Inter. 5 (2013) 12510–12519.
Choi et al. [29] reported that in their study, they found out that after the modification of the membrane with GO coating, the performance remained basically unchanged; however, within measurement errors, regardless of the number of GO bilayers on the PA membrane surface. As per Choi et al. [29], this result was quite intriguing because usually one would expect that the GO surface coating would reduce the water flux, because upon applying the GO coating on the PA membrane surface, it will become smoother, thereby resulting in a decreased effective contact area and increased hydrodynamic resistance. Choi et al. [29] attributed this unique phenomenon, in all probability, to the unique water transport (frictionless and super fast) through the stacked GO nanosheets [16]. Choi et al. [29] concluded that they successfully developed a dual-action robust coating strategy to improve the fouling and chlorine-induced degradation resistance of PA membranes via a layer-by-layer (LbL) deposition technique of graphene oxide (GO) nanosheets onto the PA membrane. The membranes fabricated by Choi et al. [29] were reported to have good membrane permeability compared with conventional coatings, where normally a flux decline is noticed. This was reported by Choi et al. [29] to be due to the unique water transport mechanism between GO nanosheets. Sun et al. [4] successfully verified water purification and ion penetration (which is rather selective) properties/characteristics of freestanding graphene oxide (GO) membranes. Membranes reinforced with freestanding GO were fabricated by Sun et al. [4] using a simple drop-casting method. The ion penetration studies of the prepared GO membranes were done using a homemade plastic sink that was separated by a plastic plate (Fig. 4). Sun et al. [4] concluded that the sodium salts permeated very quickly through the GO membranes; however, heavy metal salts permeated much more slowly compared with sodium salts. Sodium salts permeated through GO membranes quickly, whereas heavymetal salts infiltrated much more slowly. A rather interesting result was observed in the case of copper salts; they were entirely blocked by the GO membranes along with organic contaminants. Sun et al. [4] reported that salts such as copper sulfate and organic contaminants such as rhodamine B were entirely blocked by the GO membrane, owing
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Fig. 4 A schematic representation of the ion penetration technique used by Sun et al. [4] and penetration behavior of different ions through GO membranes. Reproduced with permission from P. Sun, M. Zhu, K. Wang, M. Zhong, J. Wei, D. Wu, Z. Xu, H. Zhu, Selective ion penetration of graphene oxide membranes, ACS Nano 7 (2013) 428–437.
to their strong interactions with the GO membrane. According to Sun et al., [4] graphene-derivative incorporated polymer membranes have a promising future in the field of barrier and wastewater purification technologies. Baek et al. [30] reported the successful fabrication of vertically aligned carbon nanotube (VA CNT) membranes, and claim it to be the next-generation membrane due to its fast water transport and antimicrobial properties. The vertically aligned carbon nanotube membrane was synthesized onto a Si wafer from a Fe catalyst using the waterassisted thermal chemical vapor deposition method by Baek et al. [30]. The schematic representation of the membrane fabrication and its casting is shown as Fig. 5. Fig. 6 shows the water flux of the VACNT membrane with its enhancement factor compared with that of the commercially available UF membrane [30]. Baek et al. [30] report that the VACNT membrane showed water flux that was about three times faster than the commercially available UF membrane. However, as per Baek et al. [30], it should be clearly noted that the VACNT membrane achieved this high water flux even with its smaller pore diameter, lower pore density, and thickness that was approximately 2000 times more. Baek et al. [30] also reported that the produced VACNT membrane showed better biofouling resistance than the conventional commercially available UF membrane, by approximately 15% less permeate flux reduction and 2 logs of less bacterial attachment compared with that of the UF membrane. Recently Dai et al. [31] reported the use of multi-walled carbon nanotubes to improve the performance of laccase-carrying electrospun fibrous membranes (LCEFMs). The authors used the technique of electrospinning to fabricate the laccase-carrying electrospun fibrous membranes (LCEFMs). The authors reported 90% removal efficiency of the pollutant bisphenol A from water using MWCNTsLCEFMs. The morphologies of MWCNTs-LCEFMs modified by MWCNTs (1.5 wt%) were characterized by SEM (under different resolutions), and the images are shown in Fig. 7. The authors reported the fabrication of bead-free, continuous, and randomly arrayed linear fibers of MWCNTs-LCEFMs [31]. Based on previous reports, the authors also concluded that the addition of MWCNTs could augment the conductivity of the spinning solution, thus leading to a decrease of the fiber
Fig. 5 Schematic representation of vertically aligned carbon nanotube membrane fabrication; (A) transfer of VACNTs to the tape, (B) infiltration of epoxy into the vacant areas of VACNTs utilizing the cast, and (C) fabrication of the VACNT membrane utilizing microtome. Reproduced with permission from Y. Baek, C. Kim, D.K. Seo, T. Kim, J.S. Lee, Y.H. Kim, K.H. Ahn, S.S. Bae, S.C. Lee, J. Lim, K. Lee, J. Yoon, High performance and antifouling vertically aligned carbon nanotube membrane for water purification, J. Membr. Sci. 460 (2014) 171–177. 1e+7 Water flux Enhancement factor
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Fig. 6 Water flux of the VACNT membrane with its enhancement factor compared with that of the commercially available UF membrane. Reproduced with permission from Y. Baek, C. Kim, D.K. Seo, T. Kim, J.S. Lee, Y.H. Kim, K.H. Ahn, S.S. Bae, S.C. Lee, J. Lim, K. Lee, J. Yoon, High performance and antifouling vertically aligned carbon nanotube membrane for water purification, J. Membr. Sci. 460 (2014) 171–177.
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Fig. 7 SEM micrographs of multi-walled carbon nanotubes modified laccase-carrying electrospun fibrous membranes (1.5 wt%) (MWCNTs-LCEFMs) under different resolutions: (A) 10,000; (B) 50,000; (C) 1,00,000; and (D) MWCNTs-LCEFMs with 2 wt% MWCNT loading. Reproduced with permission from Y. Dai, J. Yao, Y. Song, X. Liu, S. Wang, Y. Yuan, Enhanced performance of immobilized laccase in electrospun fibrous membranes by carbon nanotubes modification and its application for bisphenol A removal from water, J. Haz. Mat. 317 (2016) 485–493.
diameter [31–33]. The authors, however, concluded that on continuing to increase the MWCNT’s dosage in the membrane to 2.0 wt%, some beads started to appear on the fiber surface; however, the fibrous diameter was still fine [31]. According to Dai et al. [31], the fabricated MWCNTs-LCEFMs could efficiently (above 90% as shown in Fig. 8) remove the contaminant Bisphenol A from water over a wide range of pH and temperatures, indicating their excellent potential for the treatment of Bisphenol A-contaminated wastewater. Yoon et al. [34] reported the fabrication of a simple, low-cost membrane suitable for gravity-driven oil-water separation and water purification using aqueous poly(diallyldimethylammonium chloride) solution, sodium perfluorooctanoate, silica nanoparticles, and a graphene plug stacked below the membrane to remove watersoluble organics by adsorption. Yoon et al. [34] fabricated the oil water separator assembly by simply dip coating a stainless steel mesh with the abovementioned mixture (Fig. 9).
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Fig. 8 The (A) adsorption and (B) removal characteristics of bisphenol A from contaminated wastewater by multi-walled carbon nanotubes modified laccase-carrying electrospun fibrous membranes (MWCNTs-LCEFMs) with varying concentrations of MWCNTs. Reproduced with permission from Y. Dai, J. Yao, Y. Song, X. Liu, S. Wang, Y. Yuan, Enhanced performance of immobilized laccase in electrospun fibrous membranes by carbon nanotubes modification and its application for bisphenol A removal from water, J. Haz. Mat. 317 (2016) 485–493.
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Fig. 9 The oil water separator assembly fabricated by Yoon et al. [34]. Reproduced with permission from H. Yoon, S.-H. Na, J.-Y. Choi, S.S. Latthe, M.T. Swihart, S.S. Al-Deyab, S.S. Yoon, Gravity-driven hybrid membrane for oleophobic super hydrophilic oil water separation and water purification by graphene, Langmuir 30 (2014) 11761–11769.
Yoon et al. [34] used methylene blue as the contaminant to demonstrate the efficiency of their model. The biggest advantage of this technique is its simplicity and ability to be scaled up for mass production. Using the abovementioned model, water was quickly and selectively removed from oil by the composite membrane, which also had the additional capacity for water purification using the graphene plug in the system.
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Fig. 10 Schematics of oil-methylene blue (MB) separation capability as well as purification of MB by composite membrane containing a graphene plug. Reproduced with permission from H. Yoon, S.-H. Na, J.-Y. Choi, S.S. Latthe, M.T. Swihart, S.S. Al-Deyab, S.S. Yoon, Gravity-driven hybrid membrane for oleophobic superhydrophilic oil water separation and water purification by graphene, Langmuir 30 (2014) 11761–11769.
In order to prove that their model is efficient for oil-water separation and wastewater purification, Yoon et al. [34] performed another experiment in which a graphene plug was stacked below the composite membrane. Yoon et al. [34] reported that this assembly could efficiently separate hexadecane from an aqueous solution containing methylene blue and also completely decolor the methylene blue solution, indicating its removal from the aqueous media (Fig. 10).
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Conclusions
Membrane technology is established as one of the competitive treatments in the field of water purification when compared with conventional ones. The combination of various methods, along with polymer nanocomposites membranes, is very useful for removal of contaminants. Several studies have shown that carbon-reinforced polymer membranes act as a good pretreatment method of the raw water. Recent advances in the nanotechnology suggest that many of the issues involving water quality could be resolved, or greatly ameliorated, using carbon-reinforced polymeric membranes. Innovations in the development of novel technologies to desalinate water are among the most exciting and promising. Utilization of nanoparticles either embedded in membranes or on other structural media that can effectively, inexpensively, and rapidly render unusable water potable is being explored at a variety of institutions. In addition to obvious advantages for industrialized nations, the benefits for developing countries would also be enormous.
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References [1] M.A. Shannon, P.W. Bohn, M. Elimelech, J.G. Georgiadis, B.J. Marinas, A.M. Mayes, Science and technology for water purification in the coming decades, Nature 452 (2008) 301–310. [2] Y. Manawi, V. Kochkodan, M.A. Hussein, M.A. Khaleel, M. Khraisheh, N. Hilal, Can carbon-based nanomaterials revolutionize membrane fabrication for water treatment and desalination? Desalination 391 (2016) 69–88. [3] M.A. Montgomery, M. Elimelech, Water and sanitation in developing countries: including health in the equation, Environ. Sci. Technol. 41 (2007) 17–24. [4] P. Sun, M. Zhu, K. Wang, M. Zhong, J. Wei, D. Wu, Z. Xu, H. Zhu, Selective ion penetration of graphene oxide membranes, ACS Nano 7 (2013) 428–437. [5] M. Elimelech, W.A. Phillip, The future of seawater desalination: energy, technology, and the environment, Science 333 (2011) 712–717. [6] K.P. Lee, T.C. Arnot, D. Mattia, A review of reverse osmosis membrane materials for desalination—development to date and future potential, J. Membr. Sci. 370 (2011) 1–22. [7] H. El-Saied, A.H. Basta, B.N. Barsoum, M.M. Elberry, Cellulose membranes for reverse osmosis part I. RO cellulose acetate membranes including a compositewith polypropylene, Desalination 159 (2003) 171–181. [8] V. Kochkodan, N. Hilal, A comprehensive review on surface modified polymer membranes for biofouling mitigation, Desalination 356 (2015) 187–207. [9] S. Daer, J. Kharraz, A. Giwa, S.W. Hasan, Recent applications of nanomaterials inwater desalination: a critical review and future opportunities, Desalination 367 (2015) 37–48. [10] X. Song, L. Wang, C.Y. Tang, Z. Wang, C. Gao, Fabrication of carbon nanotubes incorporated double-skinned thin film nanocomposite membranes for enhanced separation performance and antifouling capability in forward osmosis process, Desalination 369 (2015) 1–9. [11] M. Tian, R. Wang, K. Goh, Y. Liao, A.G. Fane, Synthesis and characterization of high performance novel thin film nanocomposite PRO membranes with tiered nanofiber support reinforced by functionalized carbon nanotubes, J. Membr. Sci. 486 (2015) 151–160. [12] K. Balasubramanian, M. Burghard, Chemically functionalized carbon nanotubes, Small 1 (2005) 180–192. [13] W. Hoenlein, F. Kreupl, G. Duesberg, A. Graham, M. Liebau, R. Seidel, E. Unger, Carbon nanotubes for microelectronics: status and future prospects, Mater. Sci. Eng. C 23 (2003) 663–669. [14] S. Beg, M. Rizwan, A.M. Sheikh, M.S. Hasnain, K. Anwer, K. Kohli, Advancement in carbon nanotubes: basics, biomedical applications and toxicity, J. Pharm. Pharmacol. 63 (2011) 141–163. [15] M. Cadek, J. Coleman, V. Barron, K. Hedicke, W. Blau, Morphological and mechanical properties of carbon-nanotube-reinforced semicrystalline and amorphous polymer composites, Appl. Phys. Lett. 81 (2002) 5123–5125. [16] M. Hu, B. Mi, Enabling graphene oxide nanosheets as water separation membranes, Environ. Sci. Technol. 47 (2013) 3715–3723. [17] S. Stankovich, D.A. Dikin, R.D. Piner, K.A. Kohlhaas, A. Kleinhammes, Y. Jia, Y. Wu, S. T. Nguyen, R.S. Ruoff, Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide, Carbon 45 (2007) 1558–1565. [18] F. Perreault, M.E. Tousley, M. Elimelech, Thin-film composite polyamide membranes functionalized with biocidal graphene oxide nanosheets, Environ. Sci. Technol. Lett. 1 (2014) 71–76.
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[19] B.M. Ganesh, A.M. Isloor, A.F. Ismail, Enhanced hydrophilicity and salt rejection study of graphene oxide-polysulfone mixed matrix membrane, Desalination 313 (2013) 199–207. [20] A.A. Balandin, S. Ghosh, W. Bao, I. Calizo, D. Teweldebrhan, F. Miao, C.N. Lau, Superior thermal conductivity of single-layer graphene, Nano Lett. 8 (2008) 902–907. [21] B. Marinho, M. Ghislandi, E. Tkalya, C.E. Koning, G. deWith, Electrical conductivity of compacts of graphene, multi-wall carbon nanotubes, carbon black, and graphitepowder, Powder Technol. 221 (2012) 351–358. [22] M.H. Al-Saleh, U. Sundararaj, A review of vapor grown carbon nanofiber/polymer conductive composites, Carbon 47 (2009) 2–22. [23] H. Miyagawa, M.J. Rich, L.T. Drzal, Thermo-physical properties of epoxy nanocomposites reinforced by carbon nanotubes and vapor grown carbon fibers, Thermochim. Acta 442 (2006) 67–73. [24] M. Endo, Y. Kim, T. Hayashi, K. Nishimura, T. Matusita, K. Miyashita, M. Dresselhaus, Vapor-grown carbon fibers (VGCFs): basic properties and their battery applications, Carbon 39 (2001) 1287–1297. [25] B. Yadav, R. Kumar, Structure, properties and applications of fullerenes, Int. J. Nanotechnol. Appl. 2 (2008) 15–24. [26] S. Liu, T.H. Zeng, M. Hofmann, E. Burcombe, J. Wei, R. Jiang, J. Kong, Y. Chen, Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: membrane and oxidative stress, ACS Nano 5 (2011) 6971–6980. [27] L. Zhang, G.-Z. Shi, S. Qiu, L.-H. Cheng, H.-L. Chen, Preparation of high-flux thin film nanocomposite reverse osmosis membranes by incorporating functionalized multi-walled carbon nanotubes, Desalin. Water Treat. 34 (2011) 19–24. [28] P. Daraei, S.S. Madaeni, N. Ghaemi, M.A. Khadivi, B. Astinchap, R. Moradian, Enhancing antifouling capability of PES membrane via mixing with various types of polymer modified multi-walled carbon nanotube, J. Membr. Sci. 444 (2013) 184–191. [29] W. Choi, J. Choi, J. Bang, J.-H. Lee, Layer-by-layer assembly of graphene oxide nanosheets on polyamide membranes for durable reverse-osmosis applications, ACS Appl. Mater. Interfaces 5 (2013) 12510–12519. [30] Y. Baek, C. Kim, D.K. Seo, T. Kim, J.S. Lee, Y.H. Kim, K.H. Ahn, S.S. Bae, S.C. Lee, J. Lim, K. Lee, J. Yoon, High performance and antifouling vertically aligned carbon nanotube membrane for water purification, J. Membr. Sci. 460 (2014) 171–177. [31] Y. Dai, J. Yao, Y. Song, X. Liu, S. Wang, Y. Yuan, Enhanced performance of immobilized laccase in electrospun fibrous membranes by carbon nanotubes modification and its application for bisphenol A removal from water, J. Hazard. Mater. 317 (2016) 485–493. [32] J. Quan, Z. Liu, C. Branford-White, H. Nie, L. Zhu, Fabrication of glycopolymer/ MWCNTs composite nanofibers and its enzyme immobilization applications, Colloids Surf. B 121 (2014) 417–424. [33] E. Sapountzi, M. Braiek, C. Farre, M. Arab, J.F. Chateaux, N. Jaffrezic-Renault, F. Lagarde, One-step fabrication of electrospun photo-cross-linkable polymer nanofibers incorporating multiwall carbon nanotubes and enzyme for biosensing, J. Electrochem. Soc. 162 (2015) B275–B281. [34] H. Yoon, S.-H. Na, J.-Y. Choi, S.S. Latthe, M.T. Swihart, S.S. Al-Deyab, S.S. Yoon, Gravity-driven hybrid membrane for oleophobic super hydrophilic oil water separation and water purification by graphene, Langmuir 30 (2014) 11761–11769.