Original Article
Exploring the effects of graphene
oxide concentration on properties
and antifouling performance of
PEES/GO ultrafiltration membranes
High Performance Polymers
2018, Vol. 30(3) 375–383
ª The Author(s) 2017
Reprints and permission:
sagepub.co.uk/journalsPermissions.nav
DOI: 10.1177/0954008317698547
journals.sagepub.com/home/hip
Saranya Bala, Nithya D and Mohan Doraisamy
Abstract
In this study, asymmetric polyphenylene-ether-ether-sulfone (PEES) ultrafiltration (UF) membranes containing graphene
oxide (GO) were prepared via non-solvent-induced phase separation process and N-methyl pyrrolidone was used as a
solvent. The synthesis of GO was confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction
analysis. The morphology of the prepared GO nanosheets was observed by field emission scanning electron microscope
(FESEM) and transmission electron microscope. The membranes prepared with increasing concentrations of GO
nanosheets were characterized by attenuated total reflectance-FTIR, SEM, atomic force microscopy (AFM), contact angle,
and UF studies. The FTIR spectra of the GO embedded membranes reveal large amounts of –OH groups present due to
the existence of GO nanosheets which improved its surface hydrophilicity. The contact angle of PEES/GO membrane was
significantly lower than PEES membrane. The SEM pictures showed that PEES/GO UF membranes had a sponge-like
substructure with the increased porosity and pore size. An AFM topography imaging showed that roughnesses of the
modified membranes were improved compared to the pristine PEES membrane. The UF studies showed that the pure
water flux (JW) and the bovine serum albumin flux (JP) were increased with the incorporation of GO into the blend
solution. For the membrane with 0.1% GO content, JW increased by 75% and JP improved twofold which correspond to
the maximum values of 186 and 113 L m2 h1, respectively. Furthermore, the flux recovery ratio results suggested that
PEES/GO membranes have better antifouling characteristics due to the changes in membrane morphology and surface
hydrophilicity.
Keywords
Phase inversion technique, ultrafiltration membrane, antifouling properties, flux recovery ratio
Introduction
Membrane-based separation can be considered as a promising tool for water treatment processes due to its numerous
advantages.1,2 However, low flux recovery, fouling, and
high energy utilization are common drawbacks related to
membrane applications.3,4 Many attempts have been made
to improve overall membrane performance such as material
modification, polymer blending,5,6 plasma treatment, grafting with short-chain molecules,7 hydrophilic monomers,8,9
embedding nanoparticles, 10,11 and surface modification.12,13 Here, physical blending is chosen as a suitable
modification technique due to simple procedure.14 Among
the various synthetic polymers, polyphenylene-ether-ethersulfone (PEES) is a type of thermoplastic, hydrophobic
polymer. It has excellent thermal, mechanical, and filmforming properties.15 PEES has high stability and it is
resistant to oxidation even under acidic conditions.16,17
Incorporation of inorganic nanoparticles into the membrane matrix can augment the membrane hydrophilicity,
strength, permeability, antifouling performances,18,19 or
change membrane morphology.20 The blending technique
is the mixing of polymers with inorganic nanomaterials
such as silica,21 ZnO,22 TiO2,23 and recently carbon allotropes.24–26
Membrane Laboratory, Department of Chemical Engineering, Anna
University, Chennai, India
Corresponding author:
Mohan Doraisamy, Membrane Laboratory, Department of Chemical
Engineering, Anna University, Chennai 600 025, India.
Email: mohantarun@gmail.com
376
Graphene derivatives are exclusively a twodimensional structure, with an atom-layer-thickness. They
also possess a large hypothetical surface area (2630 m2/g),
high mechanical strength, and have quite nonharmful
effects.27,28 Here, graphene oxide (GO) was prepared
by the chemical oxidation method.29–31 GO is highly
hydrophilic due to existence of oxygen-containing
functional groups (e.g. hydroxyl, carboxyl, carbonyl, and
epoxy).32,33 These functional groups make GO exceptionally hydrophilic, producing fine dispersions in water, and
moreover GO can also limit the growth of Escherichia
coli.2,34 The compatibility with polymer matrices can be
enhanced due to an existence of polar group on the plane
of graphene material, but it limits inherent thermal and
electrical conductivity.35–38 Although there are many
reports on poly ether sulfone, poly ether imide, poly sulfone, polyacrylonitrile, and polyvinylidene fluoride being
blend with GO to prepare ultrafiltration (UF) membranes,
our study is the first to report the effects of GO on PEES
polymer matrix by varying GO composition. A novel and
effective membrane material PEES/GO was found for UF
applications.
In this present work, the effects of GO concentration
on permeate flux, pore size, contact angle, morphological change, porosity, and roughness parameters of the
PEES UF membrane are investigated. The prepared GO
is prepared by the modified Hummer’s method and
characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission
scanning electron microscope (FESEM), and highresolution transmission electron microscope (HRTEM)
analysis. The prepared GO is embedded into the PEES
polymer matrix by physical blending and membranes
fabricated by using immersion precipitation technique.
The change in membrane morphological structure,
surface roughness, membrane hydrophilicity, and
permeability is characterized using SEM, atomic force
microscopy (AFM), contact angle, water flux, and
rejection studies.
High Performance Polymers 30(3)
Table 1. Casting solution composition of pure PEES and PEES/
GO UF membranes.
Membrane code
M1
M2
M3
M4
M5
PEES (wt%)
GO (wt%)
NMP (wt%)
16
16
16
16
16
0
0.025
0.050
0.075
0.1
84
83.9
83.9
83.9
83.9
NMP: N-methyl pyrrolidone; PEES: polyphenylene-ether-ether-sulfone;
GO: graphene oxide; UF: ultrafiltration.
GO synthesis and characterization
GO was synthesized by modified Hummer’s method.2 It
was characterized by FTIR (Nicolet Avatar 370, Thermo
Electron Corp., Madison, WI, USA) and XRD (Bruker,
Germany) to substantiate the existence of the functional
group. The morphology of GO was examined by FESEM
(Hitachi S4800, Japan) and HRTEM (JEM 3010; Jeol Ltd.,
Tokyo, Japan) analysis.
Fabrication of membranes
PEES and PEES/GO UF membranes were prepared by nonsolvent-induced phase separation (NIPS) technique using
semiautomatic flat sheet membrane casting unit. A series of
polymer dope solutions were prepared by varying the composition of GO as shown in Table 1. Various compositions
of GO (0, 0.025, 0.05, 0.075, 0.1) wt% in NMP solvent
were dispersed by sonication for 2 h after that PEES
(16 wt%) was dissolved by constant mechanical stirring for
12 h at 55 C. The blended solution was tightly closed and
kept for 3 h to get a clear solution without air bubbles.39
The homogenous solution was again sonicated for 10 min
before casting on a glass plate and then immersed in a
(0.2%) non-solvent bath. After 10 h, the membrane was
removed and washed thoroughly with distilled water. These
fabricated membranes were stored in distilled water
containing 0.1% formalin solution at below 25 C.14
Experimental
Materials
Commercial grade of PEES pellets (Tg ¼ 465 K) was purchased from Aldrich (New Delhi, India). Analar grades of
N-methyl pyrrolidone (NMP) solvent from SRL chemicals
were acquired and stored in dried condition. Bovine serum
albumin (BSA) and phosphate buffer solution (0.5 M, pH
7.2) were procured from SRL chemicals (Mumbai, India).
Graphite powder, sodium nitrate, concentrated sulfuric
acid, potassium permanganate, and hydrogen peroxide
were procured from Aldrich. Distilled water was used for
UF experiments and preparation of gelation bath. All chemicals were used without further purification.
Characterization of membranes
ATR-FTIR. The surface chemistry of pristine PEES and
PEES/GO membranes was analyzed using ABB BOMEM
MB-3000 (Canada) attenuated total reflectance (ATR)
technique, in the range of 4000–400 cm1.
SEM. All membranes were cut into small pieces and
immersed in liquid nitrogen for 10–15 s and then kept in
a refrigerator. Frozen bits of the membranes were broken
and kept for air drying. These dry samples were loaded onto
the SEM (Hitachi, CamScan MV2300, Japan) and were
gold sputtered, and then photomicrographs were observed
at high vacuum conditions.
Bala et al.
377
Contact angle. The hydrophilicity of the membranes was
inspected through sessile drop method in goniometer
(DataPhysics, Germany). Distilled water 3 ml was carefully
dropped on the membrane surface. The contact angle was
measured within 10 s after placing the water droplet on
each membrane and obtained the average value.
AFM. Small portion of prepared membranes were cut and
stick on a metal substrate. Top surface morphology of
membranes was taken in (AFM) device (Dual ScopeTM
scanning probe-optical microscope, DME model C-21,
Denmark) by noncontact mode. The surface roughness values accounted were the average of three different scan areas
of 5 mm 5 mm each.
Porosity and mean pore radius. Membranes were cut into
required size, were initially soaked in distilled water, and
then weighed after wiping surface water with filter papers.
The wet membrane was dried in a vacuum oven at 55 C for
24 h before it was weighed. From the two weights, the
membrane porosity was calculated using the following
formula:
"¼
Ww Wd
100
Ah
ð1Þ
where Ww is the wet weight of the membrane (g), Wd is the
dry weight of the membrane (g), A is the membrane area
(m2), h is the membrane thickness (m), and is the density
of water.13 Guerout–Elford–Ferry equation (equation 2)
was utilized to examine membrane pore radius (rm) on the
basis of pure water flux and porosity data.
rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
8ð2:9 1:75"ÞlQ
ð2Þ
rm ¼
"ADP
where is the water viscosity (8.9 104 Pa s), Q is the
volume of pure water permeated per unit time (m3/s), and
DP is the operating pressure.39
Permeation experiments. The prepared membranes were cut
into desired shapes and fixed in UF cell to measure the
permeation flux and antifouling properties of membranes.
In the first 30 min, membranes were compacted at 414 KPa
and then the pure water flux (JW1) was measured for every 1
h by reducing the pressure to 345 KPa, until the steady-state
value obtained. After that, pure water was changed to BSA
(0.1 wt%) used in the present study and was prepared by
dissolving in phosphate buffer solution (PBS) (0.5 M, pH
7.2). Further, the permeate flux (JP) was recorded at specific time intervals. After filtering feed solution, the used
membrane was rinsed thoroughly with distilled water three
times, then again the water flux (JW2) recovered using distilled water was measured. The permeation flux was
defined using the following equation:
JW ¼
Q
A:Dt
ð3Þ
Figure 1. FTIR spectrum of prepared graphene oxide (GO).
FTIR: Fourier transform infrared.
where JW is the pure water flux (l m2 h1), Q is the
quantity of water permeated (l), Dt is the sampling time
(h), and A is the membrane area (m2).39
To evaluate the antifouling property of PEES/GO blend
membranes, the flux recovery ratio (FRR) was calculated12
using the following expression:
FRRð%Þ ¼
JW 2
100
JW 1
ð4Þ
Results and discussion
The FTIR spectrum of the synthesized GO is shown in
Figure 1. The GO curve shows a broad peak around 3429
cm1 corresponding to O–H stretching vibration and the
peak at 1722 cm1 is due to the C¼O strong carbonyl
stretching.40 The peaks at 1386 and 1217 cm1 correspond
to C–OH and C–O–C stretching vibrations, respectively.
This confirmed that the carboxylic acid groups are formed
on the surface of graphene. The peak around 1088 cm1 is
due to the C–O stretching vibrations of the epoxides group
in the GO layers and peak 1622 cm1 is attributed to vibration of the adsorbed water molecules as well as from contributions of the aromatic C¼C.41,42 From the results, it can
be confirmed that GO was prepared effectively. Other
researchers also reported the similar results.43,44
Figure 2 shows the XRD spectrum of graphite and GO.
Pristine graphite shows intense sharp peak at 2 ¼ 26.36 ,
whereas the GO illustrates a small peak at 2 ¼ 10.95
with d-spacing of 0.846 nm. The d-spacing of GO is larger
than that of graphite layer 0.335 nm, which confirms the
presence of the highly oxidized GO, and this increase is
mainly due to the chemical oxidation that disrupts the
ordering of graphite layers and introduces various oxygen
functional groups in the graphite.45 The TEM and FESEM
images of prepared GO nanosheets are shown in Figure 3.
From the FESEM image, it can be visualized that the GO
378
Figure 2. XRD images of graphite and graphene oxide. XRD:
X-ray diffraction.
Figure 3. TEM and FESEM images of graphene oxide nanosheets.
FESEM: field emission scanning electron microscope; TEM:
transmission electron microscope.
nanosheets tend to assemble together to form a multilayer
agglomerates. The individual nanosheets have sizes
extending from tens to hundreds of square nanometer.46
The HRTEM image shows each of single GO nanosheets
with transparency and a number of GO nanosheets are
arranged as layer by layer structure. It confirmed that
large flakes of GO having few layer thickness were prepared successfully.
The ATR-FTIR spectrum of pristine PEES and PEES/
GO blend membrane is shown in Figure 4. The pure PEES
membrane showing a C–H stretching frequency of the benzene ring at 1596 cm1, the aromatic bands at C¼C bond
stretching frequency at 1482 cm1, and aromatic ether
bond around 1264 cm1 are observed. The symmetric and
asymmetric stretching frequencies of SO2 group present in
pure PEES membrane showed strong peaks at 1186 and
1223 cm1, respectively. In comparison with pure PEES
membrane, the GO-modified membranes (M3, M4, and
M5) had intense broader peaks at *3400 cm1, which
signified that the surface hydrophilicity was evidently
improved as the GO occupied the top surface. Similar
High Performance Polymers 30(3)
Figure 4. ATR-FTIR spectrum of PEES (M1), PEES/GO (0.05%)
M3, PEES/GO (0.075%) M4 PEES/GO (0.1%) M5 ultrafiltration
membranes. ATR-FTIR: attenuated total reflectance-Fourier
transform infrared spectroscopy; PEES/GO: polyphenylene-etherether-sulfone/graphene oxide.
results were observed in other researchers also.47 The peaks
at 2857 cm1 corresponded to C–H bond.
The cross-sectional SEM images of pristine PEES and
PEES/GO membranes are shown in Figure 5. The pristine
PEES (M1) membrane has dense sponge-like structure. The
morphology of PEES/GO membranes was deviated from
that of pure PEES membrane. The GO-incorporated membranes have an asymmetric structure prepared by NIPS
technique, which typically controls a quite thin skin (high
resistance to material transport) to hold up on a much
thicker sponge-like substructure (less resistance to material
transport).13 The M2 membrane has fewer numbers of
voids with spongy structure but the pores were not completely opened. The membrane M3 showed (0.025–0.05%
GO) top skin layer and few number of interconnected
pores in sublayer. On further increase in GO composition
(0.05–0.075% and 0.1%), there are a greater number of
macrovoids throughout the membrane cross section.
This evidences that the incorporation of GO into the
blend solution forms greater number of voids across the
membrane surface which results in high porosity and
pore size.2,43
The surface hydrophilicity of the membrane, determined by the contact angle measurement, plays a significant role in the flux and antifouling performance of the
membrane. From Table 2, it can be seen that pristine
PEES membrane has a contact angle of 96.4 + 1.8,
which gradually reduced to 92.5 + 0.9, 85.6 + 1.5,
79.2 + 1.2, and 72.3 + 0.8 on increasing the concentration of GO. Incorporation of GO into the membrane
shows decrease in the measured contact angle due to the
Bala et al.
379
Figure 5. Cross-sectional SEM images of PEES and PEES/GO ultrafiltration membranes. SEM: scanning electron microscope; PEES/GO:
polyphenylene-ether-ether-sulfone/graphene oxide.
existence of large amounts of –OH groups on the membrane surface.
The hydrophilicity is inversely proportional to the contact angle. These measurements confirm that even a small
amount of GO improves the hydrophilicity of the membrane.39 The effects of GO composition on the porosity and
mean pore size of the prepared membranes are recorded in
Table 2. The increase in GO composition gradually
improved both porosity and mean pore size, which is consistent with the SEM results also. GO accelerated the diffusion rate between gels (water) and solvent (NMP). The GO
nanosheets assist the generation of polymer poor phase due
to microphase separation and this could be beneficial for
the development of membranes with high porosity and
mean pore size.33,48
AFM was used to scrutinize the surface morphology and
surface roughness of the GO-embedded membranes. The
top surface morphologies of the M1, M3, and M5 membranes are shown in Figure 6. From the topography imaging, we have concluded that PEES and PEES/GO
membranes have a nodule-valley-like arrangement. In
these images, the brightest spot corresponds to the highest
380
High Performance Polymers 30(3)
Table 2. Porosity, mean pore radius, and contact angle of pure
PEES and PEES/GO UF membranes.
Membrane
code
M1
M2
M3
M4
M5
Porosity
(") (%)
43.2
47.5
51.8
54.2
65.6
+ 0.6
+ 0.2
+ 0.9
+ 0.5
+ 0.8
Mean pore radius
(rm) (109 m)
45.61 +
51.85 +
58.78 +
63.56 +
72.69 +
0.08
0.10
0.02
0.05
0.15
Contact angle
(deg)
96.4 +
92.5 +
85.6 +
79.2 +
72.3 +
1.8
0.9
1.5
1.2
0.8
PEES: polyphenylene-ether-ether-sulfone; GO: graphene oxide; UF:
ultrafiltration.
points or nodules on the membrane surface and a dimmer
region represents the valleys or membrane pores. Pristine
PEES membrane has low surface roughness than PEES/GO
membranes; the surface properties of the PEES membrane
were changed significantly by blending PEES with GO.
The roughness parameters Ra, Rq, and Rz of membrane
surface are presented in Table 3, which was calculated for
a scanning area of 5 mm 5 mm. With the increase in
composition of GO nanosheets in the PEES/GO membranes, the roughness parameters are also increased. This
possibly reveals that the hydrophilic nature of GO directs to
a faster exchange of solvent and non-solvent during the
Figure 6. AFM images of (M1) PEES, (M3) PEES/GO (0.05%), and (M5) PEES/GO (0.1%) ultrafiltration membranes. AFM: atomic force
microscopy; PEES/GO: polyphenylene-ether-ether-sulfone/graphene oxide.
Bala et al.
381
Table 3. Surface roughness parameters of M1, M3, and M5
membranes.
Surface roughness (mm)
Membrane code
M1
M3
M5
Rq
Ra
Rz
0.012 + 1.4
0.013 + 2.4
0.016 + 1.8
0.009 + 1.6
0.011 + 2
0.013 + 2.2
0.085 + 12.4
0.106 + 14.8
0.167 + 18.6
Figure 8. Effect of GO content on flux recovery ratio. GO:
graphene oxide.
Figure 7. Effect of GO loading percentage on water permeation
flux. GO: graphene oxide.
NIPS process. The increase in the rate of solvent exchange
accounts for the spheres or nodules on the top surface of the
membrane, which accounts for its greater roughness.2,43
The influences of GO nanosheets on water permeation
flux through the embedded membranes were investigated
using a UF system. Figure 7 illustrates the resultant pure
water flux (JW1) and permeation flux (JP) of pristine PEES
and PEES/GO UF membranes. The JW1 of the membranes
is increased on incorporation of greater quantity of GO.
The membrane with the GO content of 0.1% reached maximum value of JW1 186 L m2 h1 and which is a 75%
increase compared with pure PEES membrane. The GOmodified membranes attract hydrophilic substances by
dipole–dipole interaction, hydrogen bonding, and dispersion forces.48 Similarly, JP reached its peak value of 113
L m2 h1, which increased twofold compared with pure
PEES membrane. This improvement of JW1 and JP flux
values confirms that there is a significant increase in membrane hydrophilicity (Table 2), and this enhancement of
flux is because of attraction of the water molecules to the
membrane matrix and which assists their passage through
the membrane.39
In addition, the increase in both porosity and pore size
also improved water permeability (Table 1). The extent of
flux recovery after BSA fouling was evaluated by FRR.
The antifouling property of membrane was characterized
in terms of FRR during the UF of BSA protein solution.
FRR results showed that M1 membrane possessed low flux
recovery. However, even a small amount of the GO showed
significant improvement in FRR values, as seen in Figure 8.
The enhancement of flux obtained by the incorporation of
GO is due to the formation of interconnected pores in larger
number as well as the increase in pore size and the presence
of micro surface defects due to aggregation of the more
hydrophilic GO on the membrane surface.2 PEES/GO
(0.1%) membrane showed the highest FRR (83%) which
is an indication that the increase in membrane hydrophilicity made the membranes more fouling resistant to protein
fouling.47
Conclusion
The present investigation deals with the preparation of
PEES UF membranes with GO that were prepared via
immersion precipitation technique. The existence of GO
in PEES/GO membranes was confirmed by FTIR spectra.
The effect of GO on PEES UF membranes morphology,
hydrophilicity, porosity, and mean pore size of the resultant
membrane was evaluated. In PEES UF membrane, addition
of GO led to developing of more number of macrovoids
across the membrane along with increasing pore size and
porosity. Hydrophilicity of GO-embedded membranes was
significantly improved due to the large amount of hydroxyl
group existence on the membrane surface. The morphological analysis revealed that GO-incorporated membranes
have typical asymmetric structure membranes and have a
spongy sublayer in contrast to the macrovoids of the PEES
membranes. GO-modified membranes have significantly
higher surface roughness compared with pure PEES membrane. The PEES/GO membranes exhibited higher water
flux and BSA permeability than pure PEES membrane. The
382
overall results suggest that membrane hydrophilicity, water
content, porosity, morphology, and pure water flux of
PEES/GO blend membranes improved significantly by the
incorporation of GO. Thus, the higher antifouling PEES UF
membrane was developed by the incorporation of GO.
Furthermore, the flux recovery rate indicated that PEES/
GO membranes had better antifouling performances due to
the hydrophilicity enhancement.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with
respect to the research, authorship, and/or publication of this
article.
Funding
The author(s) disclosed receipt of the following financial support
for the research, authorship, and/or publication of this article: The
authors are grateful to thank the financial support from the Anna
Centenary Research Fellowship (Procs. No. CR/ACRF/2015/25),
Anna University, Chennai.
References
1. Jafari A, Mahvi AH, Nasseri S, et al. Ultrafiltration of natural
organic matter from water by vertically aligned carbon nano
tube membrane. J Environ Health Sci Eng 2015; 13: 51.
2. Kaleekkal NJ, Thanigaivelan A, Durga M, et al. Graphene
oxide nano composite incorporated poly (ether imide) mixed
matrix membranes for in vitro evaluation of its efficacy in
blood purification applications. Ind Eng Chem Res 2015; 54:
78997913.
3. Shi X, Tal G, Hankins NP, et al. Fouling and cleaning of
ultrafiltration membranes: a review. J Water Process Eng
2014; 1: 121–138.
4. Zazouli M, Nasseri S, Mahvi A, et al. Retention of humic acid
from water by nano filtration membrane and influence of
solution chemistry on membrane performance. Iran J
Environ Health Sci Eng 2008; 5: 11–18.
5. Rahimpour A and Madaeni SS. Poly ether sulfone (PES)/
cellulose acetate phthalate (CAP) blend ultrafiltration membranes: preparation, morphology, performance and antifouling properties. J Membr Sci 2007; 305: 299–312.
6. Peyravi M, Rahimpour A, Jahanshahi M, et al. Tailoring the
surface properties of PES ultrafiltration membranes to reduce
the fouling resistance using synthesized hydrophilic copolymer. Microporous Mesoporous Mater 2012; 160: 114–125.
7. Shi Q, Su Y, Chen W, et al. Grafting short-chain amino acids
onto membrane surface stores istprotein fouling. J Membr Sci
2011; 366: 398–404.
8. Rahimpour A. UV photo-grafting of hydrophilic monomers
onto the surface of nano-porous PES membranes for improving surface properties. Desalination 2011; 265: 93–101.
9. AbuSeman MN, Khayet M and Hilal N. Comparison of two
different UV-grafted nano filtration membranes prepared for
reduction of humic acid fouling using acrylic acid and
N-vinylpyrrolidone. Desalination 2012; 287: 19–29.
High Performance Polymers 30(3)
10. Vatanpour V, Madaeni SS, Rajabi L, et al. Boehmite nano
particles as a new nanofiller for preparation of antifouling
mixed matrix membranes. J Membr Sci 2012; 401–402:
132–143.
11. Vatanpour V, Madaeni SS, Khataee AR, et al. TiO 2
embedded mixed matrix PES nano composite membranes:
influence of different sizes and types of nano particles on
antifouling and performance. Desalination 2012; 292: 19–29.
12. Kumar R, Isloor AM, Ismail AF, et al. Permeation, antifouling and desalination performance of TiO2 nano tube incorporated PSf/CS blend membranes. Desalination 2013; 316:
76–84.
13. Rana D and Matsuura T. Surface modifications for antifouling membranes. Chem Rev 2010; 110: 2448–2471.
14. Sivakumar M, Mohan D and Rangarajan R. Preparation and
performance of cellulose acetate- polyurethane blend membranes and their applications Part 1. Polym Int 1998; 47:
311–316.
15. Ansari S, Moghadassi AR and Hossein SM. Fabrication of
novel poly(phenylene ether ether sulfone) based nano composite membrane modified by Fe2NiO4 nano particles and
ethanol as organic modifier. Desalination 2015; 357:
189–196.
16. Wang Z, Li X and Zhao C. Sulfonated poly (ether ether
sulfone) copolymers for proton exchange membrane fuel
cells. J Appl Polym Sci 2007; 104: 1443–1450.
17. Mauritz KA and Ju R. Poly [(ether ether sulfone)-co-(ether
sulfone)]/silicon oxide micro composites produced via the
sol–gel reaction for tetra ethyl ortho silicate. Chem Mater
1994; 12: 2269–2278.
18. Zhao C, Xu X, Chen J, et al. Optimization of preparation
conditions of poly (vinylidene fluoride)/graphene oxide
microfiltration membranes by the Taguchi experimental
design. Desalination 2014; 334: 17–22.
19. Yin J and Deng B. Polymer-matrix nano composite membranes for water treatment. J Membr Sci 2015; 479: 256–75.
20. Wu H, Mansouri J and Chen V. Silica nano particles as carriers of antifouling ligands for PVDF ultrafiltration membranes. J Membr Sci 2013; 433: 135–151.
21. Hassanajili S, Khademi M and Keshavarz P. Influence of
various types of silica nanoparticles on permeation properties
of polyurethane/silica mixed matrix membranes. J Membr Sci
2014; 453: 369–83.
22. Liang S, Xiao K, Mo Y, et al. A novel ZnO nano particle
blended poly vinylidene fluoride membrane for antiirreversible fouling. J Membr Sci 2012; 394: 184–92.
23. Rajaeian B, Heitz A, Tade MO, et al. Improved separation
and antifouling performance of PVA thin film nano composite membranes incorporated with carboxylated TiO2 nano
particles. J Membr Sci 2015; 485: 48–59.
24. Vatanpour V, Madaeni SS, Moradian R, et al. Fabrication and
characterization of novel antifouling nano filtration membrane prepared from oxidized multiwalled carbon nanotube/
polyethersulfone nano composite. J Membr Sci 2011; 375:
284–94.
Bala et al.
25. Zhao C, Xu X, Chen J, et al. Optimization of preparation
conditions of poly (vinylidene fluoride)/graphene oxide
microfiltration membranes by the Taguchi experimental
design. Desalination 2014; 334: 17–22.
26. Crock CA, Rogensues AR, Shan W, et al. Polymer nano
composites with graphene-based hierarchical fillers as materials for multifunctional water treatment membranes. Water
Res 2013; 47: 3984–3996.
27. Ganesh BM, Isloor AM and Ismail AF. Enhanced hydrophilicity and salt rejection study of graphene oxide-polysulfone
mixed matrix membrane. Desalination 2013; 313: 199–207.
28. Yari M, Norouzi M, Mahvi AH, et al. Removal of Pb (II) ion
from aqueous solution by graphene oxide and functionalized
graphene oxide-thiol: effect of cysteamine concentration on
the bonding constant. Desalin Water Treat 2015; 57:
11195–11210.
29. Paulchamy B, Arthi G and Lignesh BD, A simple approach to
stepwise synthesis of graphene oxide nanomaterial. J Nano
Med Nano Technol 2015; 6: 1.
30. Verdejo R, Bernal MM, Romasanta LJ, et al. Graphene filled
polymer nano composites. J Mater Chem 2011; 33: 01–10.
31. Singh V, Joung D, Zhai L, et al. Graphene based materials: past,
present and future. Prog Mater Sci 2011; 56: 1178–1271.
32. Zhao C, Xu X, Chen J, et al. Effect of graphene oxide concentration on the morphologies and antifouling properties of PVDF
ultrafiltration membranes. J Environ Chem Eng 2013; 1: 349.
33. Hegab HM and Zou L. Graphene oxide-assisted membranes:
fabrication and potential applications in desalination and
water purification. J Membr Sci 2015; 484: 95–106.
34. Ma JZ, Zhang JT and Xiong ZG, Preparation, characterization and antibacterial properties of silver-modified graphene
oxide. J Mater Chem 2011; 21: 3350–3352.
35. Hu K, Kulkarni DD, Choi I, et al. Graphene-polymer nanocomposites for structural and functional applications. Prog
Polym Sci 2014; 39: 1934–1972.
36. Novoselov KS, Fal’ko VI, Colombo L, et al. A road map for
graphene. Nature 2012; 490: 192–200.
383
37. Dreyer DR, Park S, Bielawski CW, et al. The chemistry of
graphene oxide. Chem Soc Rev 2010; 39: 228–240.
38. Kim H, Abdala AA and Macosko CW. Graphene/polymer
nano composites. Macromolecules 2010; 43: 6515–6530.
39. Saranya R, Kavitha E and Mohan D. Graphene oxide incorporated polyethersulphone membrane for heavy metal ion
removal. In: INDA-APDA conference on clean India technologies: role of desalination and water purification, Chennai,
11–13 February 2016, 61, p. 71. Tamilnadu: INDA-APDA.
40. Ganesh BM, Arun M, Isloor, et al. Enhanced hydrophilicity
and salt rejection study of graphene oxide-polysulfone mixed
matrix membrane. Desalination 2013; 313: 199–207.
41. Xu YX, Bai H, Lu GW, et al. Flexible graphene films via the
filtration of water-soluble non covalent functionalized graphene sheets. J Am Chem Soc 2008; 130: 5856–5857.
42. Shou Q, Cheng J, Zhang L, et al. Synthesis and characterization of a nanocomposite of goethite nanorods and reduced
graphene oxide for electro chemical capacitors. J Solid State
Chem 2012; 185: 191–197.
43. Wang Z, Yu H, Xia J, et al. Novel GO-blended PVDF ultrafiltration membranes. Desalination 2012; 299: 50–54.
44. Georgakilas V, Otyepka M, Bourlinos AB, et al. Functionalization of graphene: covalent and non-covalent approaches,
derivatives and applications. Chem Rev 2012; 112:
6156–6214.
45. Buchsteiner A, Lerf A and Pieper J. Water dynamics in graphite oxide investigated with neutron scattering. J Phys Chem
B 2006; 110: 22328–22338.
46. Wang GX, Wang B and Park J. Synthesis of enhanced hydrophilic and hydrophobic graphene oxide nanosheets by a solvothermal method. Carbon 2009; 47: 68–72.
47. Valcarcel M, Cardenas S, Simonet BM, et al. Carbon nanostructures as sorbent materials in analytical processes. Trends
Anal Chem 2008; 1: 27–34.
48. Zhao C, Xu X, Chen J, et al. Effect of graphene oxide concentration on the morphologies and antifouing properties of
PVDF ultrafiltration membranes. J Environ Chem Eng 2013;
1: 349–354.