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Graphene oxide membranes supported on the ceramic hollow fiber for efficientH2 recovery
Kang Huang, Jianwei Yuan, Guoshun Shen, Gongping Liu, WanqinJin
PII: S1004-9541(16)30677-2DOI: doi:10.1016/j.cjche.2016.11.010Reference: CJCHE 717
To appear in:
Received date: 15 July 2016Accepted date: 22 November 2016
Please cite this article as: Kang Huang, Jianwei Yuan, Guoshun Shen, Gongping Liu,Wanqin Jin, Graphene oxide membranes supported on the ceramic hollow fiber for effi-cient H2 recovery, (2016), doi:10.1016/j.cjche.2016.11.010
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Graphene oxide membranes supported on the ceramic
hollow fiber for efficient H2 recovery
Kang Huang, Jianwei Yuan, Guoshun Shen, Gongping Liu, Wanqin Jin*
State Key Laboratory of Materials-Oriented Chemical Engineering, College of
Chemical Engineering, Jiangsu National Synergetic Innovation Center for
Advanced Materials, Nanjing Tech University, 5 Xinmofan Road, Nanjing 210009,
PR China
*Corresponding author
Tel.: +86-25-83172266;
Fax: +86-25-83172292;
E-mail: [email protected]
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Separation Science and Engineering
Graphene oxide membranes supported on the ceramic
hollow fiber for efficient H2 recovery#
Kang Huang, Jianwei Yuan, Guoshun Shen, Gongping Liu, Wanqin Jin*
State Key Laboratory of Materials-Oriented Chemical Engineering, College of
Chemical Engineering, Jiangsu National Synergetic Innovation Center for
Advanced Materials, Nanjing Tech University, Nanjing 210009, China
*Corresponding author
Tel.: +86-25-83172266;
Fax: +86-25-83172292;
E-mail: [email protected]( W.Q. Jin)
#Supported by the National Natural Science Foundation of China (Grant Nos.
21476107, 21490585, 21406107), the Innovative Research Team Program by the
Ministry of Education of China (Grant No. IRT13070) and the Topnotch Academic
Programs Project of Jiangsu Higher Education Institutions (TAPP).
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Abstract
The special channels and intrinsic defects within GO laminates make it a very
potential candidate for gas separation in recent years. Herein, the gas separation
performance of GO membranes prepared on the surface of ceramic α-Al2O3 hollow
fiber were investigated systematically. The microstructures of ceramic hollow fiber
supported GO membranes were optimized by adjusting operation conditions. And, the
GO membrane fabricated at 30 min exhibited great promising H2 recovery ability
from H2/CO2 mixture. At room temperature, the H2 permeance was over 1.00 ×10-7
mol·(m2·s·Pa)
-1 for both single gas and binary mixture. The corresponding ideal
selectivity and mixture separation factor reached around 15 and 10, respectively. In
addition, humility, operation temperature, H2 concentration in the feed and the
reproducibility were also studied in this work.
Keywords: Graphene oxide; ceramic hollow fiber; gas separation; hydrogen recovery
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1. Introduction
Gas separation membranes are increasingly becoming an important and convenient
technology for the recovery of hydrogen from gas mixtures (H2/N2, H2/CO2,
H2/hydrocarbons and so on), oxygen-nitrogen separation, natural gas separation, CO2
capture, vapour-vapour separation and air dehydration. [1] The attractive and
significant reason is that the membrane technology can effectively separate gas
mixtures under low pressure, obviously reduce required industry area and minimize
necessary energy consumption with relatively low contamination, compared with
traditional separation technologies. [2, 3] Up to now, numerous creative works about
gas separation membranes are focused on achieving high flux and surprising
selectivity. [4-7] In order to obtain this target, three main routes are employed: 1)
designing and synthesizing new materials with special and excellent properties; 2)
improving current gas separation membrane materials by modification; 3) developing
novel and high-effective membrane processes based on current materials. The
intrinsic excellent properties of the membrane materials are the precondition to
achieve high separation performance. Beyond their outstanding properties, the
membrane materials should also satisfy other necessary practical application
conditions, such as low production cost, simple preparation process and easy scale-up.
Recently, considerable interest has been aroused by the emerging two-dimensional
structural materials, such as MoS2, [8, 9] phosphorene, [10] ZIF-7 [11] and graphene,
[12] due to their ultra-thin thickness and unique physicochemical property. Utilizing
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two-dimensional intriguing materials to fabricate thin membranes has been considered
as a useful and effective way to overcome the current permeability/selectivity
trade-off, [13, 14] which often occurred in traditional polymer membranes. [14, 15]
Among them, there is no doubt that graphene, a two-dimensional monolayer of sp2
hybridized carbon atoms arrayed in a honeycomb pattern, exhibits the most
imaginative and outstanding prospect, because of a series of unique properties, such
as good chemical stability, excellent thermal conductance and strong mechanical
strength. [12, 16-19] For example, Nair et al. found that graphene oxidce (GO, the
oxygen-containing analogue of graphene) membrane allowed unimpeded permeation
of water while other molecules were blocked, because of the low-friction flow of
water molecules through 2D capillaries between graphene sheets. [20] Subsequently,
based on this interesting discovery, significant amount of researches about GO
membranes for water treatment, [21-26] liquid organic separation [27-30] and ion
sieve [31, 32] were investigated and showed great attractive performance.
GO’s precise transport channels and atomic-scale pores also make it a potential
candidate in gas separation. Up to now, some exciting and encouraging works have
been achieved. [33, 34] However, because of the complicated membrane preparation
process, [34-36] it is very hard to transfer their membrane to the practical application.
On the other hand, the attractive ultrathin flat membrane structure brings another
critical issue: how to bear complex and harsh long-term operation environments in the
real industry (such as high pressure and unstable gas flow). Usually, extremely careful
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manipulations are needed for these few-layers GO membranes. [33, 34] Therefore, it
is still necessary to design GO membranes which can satisfy the practical
requirements and explore their gas separation.
In order to make up above shortages, we are apt to prepare porous ceramic supported
GO membranes, because porous ceramic substrates not only can decrease thickness of
membranes to realize high flux obviously, but also can offer a good mechanical
strength for composite membranes. [37, 38] In this study, the porous ceramic hollow
fiber was selected as the substrates due to its characteristic configuration (low mass
transfer resistance and high-packing density) and good chemical and thermal stability.
[39] Previously, we have proposed a convenient and rapid vacuum suction method to
prepare GO membranes on the ceramic hollow fiber, which exhibited excellent
pervaporation separation performance. [27] The special configuration makes GO
membranes very easy to be scale-up. In addition, GO nanosheets stacked to form a
cylinder shell around the ceramic hollow fiber, keeping it more stable than flat GO
membranes. Herein, we will deeply study the gas separation performance of the
ceramic hollow fiber supported GO membranes by: 1) optimizing microstructures of
GO membranes; 2) exploring gas separation ability systemically, including single gas
and binary mixture; 3) investigating stability of GO membranes in the gas system.
Small gas molecules (H2, CO2, N2, O2 and CH4) will be employed to investigate the
potential separation in the whole study.
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2. Experimental
2.1 Materials
GO powder prepared by modified hummer’s method [40] was purchased from
Nanjing JCNANO Tech Co., Ltd, China. The ceramic -Al2O3 hollow fiber support
was prepared as our previous method. [7] 99.999% H2, H2, CO2, N2, O2 and CH4 were
used as the gas sources, which were brought from Nanjing Special Gas Co., LTD,
China. Deionized water were also employed in the whole experiment.
2.2 Preparation of GO membrane
A typical process to prepare GO membranes is described as follow: Firstly,
preparation of GO aqueous solution. GO powder was dissolved into deionized water,
and at the same time the mixture solution was treated by ultrasound equipment for 1
hour to form a high concentration GO aqueous solution. In this step, GO powder was
exfoliated to nanosheets. Then, above GO solution was centrifuged at 3000 r·min-1
for
10 min in order to remove agglomerated powder and impurity. After this, the
as-prepared solution was diluted 1000 times to form a very low concentration solution
(about 0.001 mg·ml-1
). Secondly, fabrication of GO membranes. The GO
membrane was prepared by our previous reported method (i.e., Vacuum Suction
method). [27] The detailed steps are listed as below. One side of the ceramic hollow
fiber was sealed and the other side was connected to a vacuum pump. Then, the whole
hollow fiber was immersed in the GO aqueous solution. With the pressure driving,
GO flakes were stacked on the surface in order. Through changing the operation time,
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different thickness GO membranes were fabricated. Finally, the as-prepared GO
membrane was dried in a vacuum oven at 45 oC over 48 h. The quality of as-prepared
GO membranes were examined by testing the H2 and CH4 single gas permeation.
2.3 Characterization
The morphologies of the GO membranes and the ceramic hollow fiber were
characterized by field emission scanning electron microscope (FESEM S4800,
Hitachi, Japan). The working parameters were a voltage (HV) of 5 kV and a work
distance (WD) of 8 mm. Fourier transform infrared spectroscopy were recorded by
using a FTIR spectrophotometer (AVATAR-FT-IR-360, Thermo Nicolet, USA) over
the range of 4000-500 cm-1
. The X-ray photoelectron spectroscopy (XPS) was carried
out through an X-ray photoelectron spectrometer (Thermo ESCALAB 250, USA)
with monochromatized Al K radiation. Atomic force microscopy (AFM, XE-100,
Park Systems, Korea) was used to detect the size of GO flakes and the surface
morphologies of the GO membrane.
2.4 Gas permeation test
Gas permeation experiments were performed by small gas molecules (H2, CO2, N2, O2
and CH4) on the permeation setup. Fig. 1 shows the schematic of the gas separation
setup. All the measurements were performed using the Wicke–Kallenbach technique
with an on-line gas chromatography (Agilent Technologies 7820A) at room
temperature. Before test, the membrane was activated at 45 oC. And, all the results
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were tested three times, making sure that the results were reliable.
For the single gas measurement, the feed flow rate was set to 30 ml·min-1
. When
studying the influence of humidity, the dried gas flow would go through a water bottle.
For the binary mixture, the feed side was fed at a total volumetric flow rate of 60
mL/min with each gas of 30 ml·min-1
. When investigating the influence of H2 fraction
in the feed, the total flow kept at 60 ml·min-1
. In all measurements, helium was used
as sweep gas at a flow rate of 30 ml·min-1
. Atmosphere pressure was applied to both
sides of the permeation cell. The temperature was controlled by a circulation oven.
The membrane permeance (Fi) is defined as:
AP
NF
i
ii
Where iN is the permeate rate of component i (mol·s
-1),
iP is the
transmembrane pressure difference of i (Pa), and A is the effective membrane area
(m2).
The ideal selectivity is calculated by the ratio of single gas permeances.
The separation factor was calculated as:
ji
ji
jixx
yy
/
/,
Where x and y are the molar fraction of the one component in the feed and
permeate, respectively.
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Fig. 1. Schematic diagram of the gas separation setup. “MFC” and “GC” are mass flow controller
and gas chromatography (Agilent Technologies 7820A), respectively. “F” and “P” are the flow
rate and pressure, respectively.
3. Results and Discussion
3.1 Basic characterization of GO materials and hollow fiber support
As we know, the properties of membrane materials have great effect on the eventual
separation performance. Before experiments, we first characterized the basic
properties of GO materials, including AFM, FTIR, XPS and Raman spectrum. Fig.
2(a) shows the AFM image of GO flakes deposited on the mica substrate. The size of
GO flake is about 1 m size. The depth profile indicates that the GO sheet is
approximately 1 nm in thickness. The FTIR spectrum (Fig. 2(b)) proves the presences
of O–H stretching vibrations (3415 cm-1
), C=O stretching vibrations from carbonyl
and carboxylic groups (1733 cm-1
), unoxidized sp2 C=C bonds in the carbon lattice
(1624 cm-1
), and C–O stretching vibrations from epoxy groups (1051 cm-1
). These
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functional groups were further confirmed by the XPS measurement. As shown in Fig.
2(c), the XPS C1s spectrum of GO clearly indicates four kinds of C atoms in different
functional groups: C–C (~284.8 eV), C–O (~286.8 eV), C=O (~287.8 eV), and C(O)O
(~289.0 eV). The C–O groups (representing hydroxyl and epoxide groups) comprise
approximately 45.3% of the total C1s peak area, whereas C=O and C(O)O are 11.07%
and 5.4%, respectively. The results show that the ratio of O/C in GO is approximately
0.6, which is relatively high as compared to the reported values. [41] XPS and FTIR
results are well in agreement with the Lerf-Klinowski Model of the GO sheet. [42, 43]
When the Hummer method produced amount of oxygen-containing groups, some
intrinsic defects were also created at the same time. The present of defects can be
supported by the Raman spectrum. As shown in Fig. 2(d), the ID/IG ratio of the GO
powder is about 1.05, which be assigned to higher defects/disorders in the GO flake.
[33] The diverse carbon functional groups and intrinsic defects on the GO structure
will be beneficial for the gas separation through the molecular interaction and sieving.
The structure of the ceramic hollow fiber was also investigated. Fig. 2(e) gives an
optical picture of the hollow fiber and the traditional ceramic tube support. Compared
with tube, the hollow fiber owns a slender shape with smaller diameter (about 1.5
mm), implying a higher packing density. Fig. 2(f) shows the detail features of the
hollow fiber by FESEM. Its asymmetric structure (i.e., a thin separation dense layer
integrated with finger-like porous layers on both sides in Fig. 2(f-i) reduces the mass
transfer resistance of supports. The relatively smooth surface makes (Fig. 2(f-ii)) GO
sheets easy to stack and reduces the formation of big holes.
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Fig. 2. (a) AFM image of GO flakes deposited on the mica substrate; (b) FTIR, (c) XPS and (d)
Raman spectrum characterization of GO; (e) Optical picture of the ceramic tube and hollow fiber;
(f) FESEM images of the ceramic hollow fiber (insert i: cross-section; insert ii: surface).
3.2 Optimizing structures of GO membranes
In order to obtain high flux and selectivity, the microstructures of the hollow fiber
supported GO membranes were optimized systematically. By adjusting the
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preparation time, GO membranes with different thickness were achieved. Fig. 3
shows that the thickness of the GO membranes increases with the operation time
increasing. However, there is a nonlinearity between the membrane thickness and
operation time. The reason is that the resistance was reinforced with increasing the
membrane thickness, which inhibited more GO sheets to stack on the surface. The
insert in Fig. 3 presents two typical GO membranes prepared at 10 and 120 min,
respectively. Obviously, the membrane colour becomes darker when the thickness
increases. Additional, both of them show a continuous and uniformly layer, indicating
that the vacuum suction method is very effectively to fabricate tubular GO
membranes.
Fig. 3. The thickness of the ceramic hollow fiber supported GO membrane as a function of the
membrane preparation time.
Fig. 4 shows the microstructures of three typical GO membrane which were prepared
at 5, 30 and 120 min, respectively (the corresponding membranes are marked as T5,
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T30 and T120, respectively). When the time is too short, there are some pin holes on
the surface of GO membrane (Fig. 4(a)). The insert of Fig. 4(a) gives a clearer and
enlarged image. From Fig. 4(b) and Fig. 4(c), continuous and complete membranes
can be observed. And, the surface becomes smoother with the growth of thickness.
Fig. 4(d), 4(e) and 4(f) exhibit the corresponding cross-section images of T5, T30 and
T120 membranes, respectively. All of them attach well with the ceramic hollow fiber,
which may be attributed to the hydrogen bond between the oxygen containing
functional groups of the GO membrane and the hydroxy group on the surface of the
ceramic hollow fiber.
Fig. 4. FESEM images of the GO membrane prepared under different operation time: (a-c) the
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surface images; (e-f) the cross-section images.
Gas separation measurements of single H2 and CH4 were utilized to examine the
membranes’ quality. As shown in Fig. 5, the gas permeances of H2 and CH4 decline
together, when the membrane thickness increases. But the H2/CH4 selectivity of T30
GO membrane gets a peak and meanwhile the membrane still has a good H2
permeance. Obviously, with increasing the membrane thickness, the H2 permeance
declines quickly. This is why Nair et al. found the thick GO membrane was
impermeable to gases because of the higher membrane thickness. [20] Considering
permeance and selectivity, we selected the 30 min operation time as the most
optimized condition to prepare the ceramic hollow fiber supported GO membranes.
Fig. 6 shows the FESEM image of T30 GO membrane after rotating 45° and the
corresponding AFM image, indicating that the membrane is very intact with lots of
ripples and the membrane thickness is about 300 nm. The corresponding XRD result
(the inset in Fig. 6(a)) shows the d-spacing size of the GO membranes is ~ 0.81 nm.
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Fig. 5. The H2 and CH4 permeance and corresponding H2/CH4 selectivity of GO membrane as a
function of the membrane preparation time.
Fig. 6. (a) FESEM image and (b) AFM image of T30 GO membrane. The inset of (a) is the XRD
result.
3.3 Single gas separation performance
Single gas permeations of T30 GO membrane, including H2, CO2, O2, N2 and CH4,
were tested in detail. From Fig. 7, the permeances of these small gas molecules
decreases in the order H2 > CH4 > N2 > O2 > CO2, with increasing the molecular
weight. The corresponding ideal selectivity (Fig. 8) of H2/CO2, H2/O2, H2/N2 and
H2/CH4 are 15.0, 7.5, 7.2 and 6.4, respectively. In contrast to other gases, CO2 shows
a sharp down in the permeance and the highest hydrogen selectivity, which can be
attributed to the chemical nature of GO material. As we know, there are numerous
carboxylic acid groups distributed at the edge of GO flakes. Strong interplay between
these polar groups and C-O bonds in the nonpolar CO2 molecules would happen. For
CO2 transfer, CO2 as a Lewis acid or a Lewis base participates in hydrogen bonding,
which inhibits it from transferring within the stacked GO structure. [34] The similar
phenomenon was also found in the porous metal-organic framework (MOF) ZIF-78
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membrane. [44] The two polar functional groups –NO2 in ZIF-78 structure made it
exhibit the highest affinity for CO2, which blocked the diffusion of CO2 molecules
through the ZIF-78 channels.
Fig. 7. Single gas permeance (H2, CO2, O2, N2 and CH4) with dry feed or hydrated feed as a
function of the molecular kinetic diameter.
Then, we investigated the influence of humidity for the gas transfer. As shown in Fig.
7, most gas permeances (except CO2) decreases when the humid steam is added in the
feed, because the water molecules in the GO channels limits the gas transfer.
However, a slight increase of CO2 is observed. Kim et al. [34] found the same trend
when GO membrane was used to separate humid gas. This result further confirms that
CO2 molecules have special interaction with the carboxylic acid groups in GO.
Because of the growth of CO2 permeance, the corresponding H2/CO2 ideal selectivity
declines obviously under the wet condition (Fig. 8), indicating that wet gas has
disadvantages for hydrogen recovery from H2/CO2 mixture.
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Fig. 8. Selectivity of H2/CH4, H2/N2, H2/O2 and H2/CO2 with dry feed or hydrated feed
3.4 Binary gas separation performance
Single gas measurements only can give the ideal selectivity, because the gas
molecular transfer in this process is relatively independent. However, interplays
between different gases are generally not negligible, which may result in a prominent
deviation of the mixture separation factor from the ideal selectivity. Table 1 lists all
the single gases and binary mixtures separation performances. Like single gas test, the
ceramic hollow fiber supported GO membrane shows a same regular for mixtures.
But the corresponding permeance and separation factor has a bit of decrease because
of the competitive adsorption and diffusion between different gas molecules. This
phenomenon was often observed in zeolite membranes. For example, a CVD
modified ZSM-5 membrane exhibited a higher H2/CO2 ideal selectivity (17.5) than
the mixture separation factor (10.8). [45] Another AlPO4 membrane also showed a
lower separation factor (9.7) in H2/CO2 binary system than the ideal selectivity of
23.9. [46] Generally speaking, although the H2/CO2 separation factor drops, it still
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reveals a useful separation ability (10.2) for practical hydrogen recovery application.
The Robeson plot for H2-CO2 selectivities versus CO2 permeabilities of polymer
membranes has been widely used to compare the performance of membranes.[47] As
shown in Fig. 9, our GO hollow fiber membranes exhibit superior properties.
Table 1. Single gases and binary mixtures separation performances under dry state.
Permeance×107
/ mol ·m-2
·s-1
·Pa-1
H2 ideal selectivity H2 separation factor
Single gas
H2 1.34 —
CO2 0.09 14.98
O2 0.18 7.48
N2 0.19 7.21
CH4 0.21 6.37
Mixed gas
H2 (50 vol% in CO2) 1.20 10.22
CO2 (50 vol% in H2) 0.11
H2 (50 vol% in O2) 1.04 4.69
O2 (50 vol% in H2) 0.20
H2 (50 vol% in N2) 1.03 4.43
N2 (50 vol% in H2) 0.21
H2 (50 vol% in CH4) 1.24 4.67
CH4 (50 vol% in H2) 0.24
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Fig. 9. Comparison of H2/CO2 gas separation performances of GO hollow fiber membranes with
Robeson upper bound[47].
3.5 Effect of the H2 concentration in the feed for H2/CO2 mixture
In general, the H2/CO2 rate in the real mixture is very complicated and cannot be one
to one. In order to assess the influence of the feed composition on the hydrogen
recovery, the separation of H2/CO2 binary mixture was explored under different H2
concentrations in the feed. As shown in Fig. 10, with increasing the H2 concentration,
the H2 permeance has a slight growth because of the enhanced driving force. In
contrast, an imperceptible downtrend exists in the CO2 permeance line. As a result,
the H2/CO2 separation factor is almost unchanged and almost keeps a constant (about
10), which is independent of H2 fraction in the feed.
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Fig. 10. Effect of the H2 concentration in the feed for H2/CO2 mixture separation performance.
Fig. 11 presents the corresponding H2 and CO2 fraction in the permeate as a function
of H2 concentration in the feed. Obviously, a high H2 concentration mixture over 90%
in volume will be obtained, when the feed is equimolar. According to Fig. 11, for 20%
H2 concentration of H2/CO2 mixture, the finally H2 concentration mixture will be
more than 95% only after twice purification in theory.
Fig. 11. H2 and CO2 fraction in the permeate as a function of H2 concentration in the feed
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3.6 Effect of temperature on H2/CO2 separation
Fig. 12 represents the variation of the H2 and CO2 permeances and their
corresponding separation factors from their equimolar binary mixture in the
temperature of 50-200 oC. Both the permeances of H2 and CO2 increase quickly with
increasing operation temperature because of an activated diffusion process. The
corresponding separation factor shows a down trend, indicating that some inevitable
pores were formed in the GO laminates by heating. On the other hand, these pores
would also contribute to improving the permeance. X-ray photoelectron spectroscopy
(Fig. 13) shows that most of the oxygen containing functional groups have
disappeared after heating treatment, implying that this process is irreversible.
Therefore, low temperature (room temperature) is very suitable for GO membrane
used in gas separation industry field.
Fig. 12. Effect of temperature on H2/CO2 separation
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Fig. 13. X-ray photoelectron spectroscopy result of the GO membrane after heating treatment.
3.7 Repeatability and Stability of GO hollow fiber membranes
As shown in Table 2, the ceramic hollow fiber supported T30 GO membranes exhibit
very good repeatability on the separation of equalmolar H2/CO2 binary mixture at
room temperature. All the membranes were prepared under the same conditions. The
single permeaces of H2 and CO2 are around 1.3×10-7
and 0.09 ×10-7
mol·m-2
·s-1
·Pa-1,
respectively, and the corresponding ideal selectivity is around 15. For binary mixture,
the as-prepared GO membranes show similar results as listed in Table 2. This well
reproducibility will benefit to the practical application. What’s more, we also
summarize the H2-CO2 separation performance of one of the as-prepared GO hollow
fiber membranes during the whole test process. As shown in Fig. 14, the GO hollow
fiber membrane showed a very good stability under different test conditions.
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Table 2. Repeatability of GO membranes
No.
Single gas Mixed gas
Permeance×107
/mol·m-2
·s-1
·Pa-1
H2/CO2 ideal
selectivity
Permeance×107
/mol·m-2
·s-1
·Pa-1
H2/CO2
separation factor
H2 CO2 H2 CO2
M04 1.34 0.09 14.98 1.20 0.11 10.22
M02 1.23 0.07 16.68 1.09 0.10 10.01
M03 1.47 0.11 13.82 1.30 0.12 9.73
M01 1.41 0.09 15.74 1.21 0.12 9.30
M05 1.34 0.09 14.50 1.26 0.10 10.85
Fig. 14. The long term stability of GO hollow fiber membrane under different test conditions.
4. Conclusions
The ceramic hollow fiber supported GO membranes were studied systematically in
the present work. The optimized GO membranes possess a good balance between H2
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permeance and selectivity. Considering the uncomplicated fabrication process and
high packing density, the gas separation ability of ceramic hollow fiber supported GO
membranes will create a great amount of brilliance in the gas separation field. The
high specific surface area of GO material also makes GO membranes very attractive,
due to the resource saving and cost-effective. In addition, because of their special
oxygen containing functional groups, it may further handle the chemical nature of GO
membranes by modifying surface or channels, the gas separation ability of GO
membranes could become adjustable and various.
References
[1] P. Bernardo, E. Drioli, G. Golemme, Membrane gas separation: A review/state of
the art, Ind. Eng. Chem. Res. 48 (2009) 4638-4663.
[2] R.W. Baker, Future directions of membrane gas separation technology, Ind. Eng.
Chem. Res. 41 (2002) 1393-1411.
[3] X.-L. Li, S. Tao, K.-D. Li, Y.-S. Wang, P. Wang, Z.-J. Tian, In situ synthesis of
ZIF-8 membranes with gas separation performance in a deep eutectic solvent, Acta
Phys.-Chim. Sin. 32 (2016) 1495-1500.
[4] A.J. Brown, N.A. Brunelli, K. Eum, F. Rashidi, J.R. Johnson, W.J. Koros, C.W.
Jones, S. Nair, Interfacial microfluidic processing of metal-organic framework hollow
fiber membranes, Science 345 (2014) 72-75.
[5] Y. Hu, J. Wei, Y. Liang, H. Zhang, X. Zhang, W. Shen, H. Wang, Zeolitic
imidazolate framework/graphene oxide hybrid nanosheets as seeds for the growth of
ultrathin molecular sieving membranes, Angew. Chem. Int. Ed. 55 (2016) 2048-2052.
[6] J. Shen, G. Liu, K. Huang, Z. Chu, W. Jin, N. Xu, Subnanometer two-dimensional
graphene oxide channels for ultrafast gas sieving, ACS Nano 10 (2016) 3398-3409.
[7] K. Huang, Z. Dong, Q. Li, W. Jin, Growth of a ZIF-8 membrane on the
ACC
EPTE
D M
ANU
SCR
IPT
ACCEPTED MANUSCRIPT
inner-surface of a ceramic hollow fiber via cycling precursors, Chem. Commun. 49
(2013) 10326-10328.
[8] RadisavljevicB, RadenovicA, BrivioJ, GiacomettiV, KisA, Single-layer MoS2
transistors, Nat Nano 6 (2011) 147-150.
[9] K.G. Zhou, N.N. Mao, H.X. Wang, Y. Peng, H.L. Zhang, A mixed-solvent strategy
for efficient exfoliation of inorganic graphene analogues, Angew. Chem. Int. Ed. 50
(2011) 10839-10842.
[10] H. Liu, A.T. Neal, Z. Zhu, Z. Luo, X. Xu, D. Tománek, P.D. Ye, Phosphorene: An
unexplored 2D semiconductor with a high hole mobility, ACS Nano 8 (2014)
4033-4041.
[11] Y. Peng, Y. Li, Y. Ban, H. Jin, W. Jiao, X. Liu, W. Yang, Metal-organic
framework nanosheets as building blocks for molecular sieving membranes, Science
346 (2014) 1356-1359.
[12] A.K. Geim, Graphene: Status and Prospects, Science 324 (2009) 1530-1534.
[13] Z. Zheng, R. Grunker, X. Feng, Synthetic Two-dimensional materials: a new
paradigm of membranes for ultimate separation, Adv. Mater. (2016).
[14] Z.P. Smith, B.D. Freeman, Graphene oxide: a new platform for high-performance
gas- and liquid-separation membranes, Angew. Chem. Int. Ed. 53 (2014)
10286-10288.
[15] T.-S. Chung, L.Y. Jiang, Y. Li, S. Kulprathipanja, Mixed matrix membranes
(MMMs) comprising organic polymers with dispersed inorganic fillers for gas
separation, Prog. Polym. Sci. 32 (2007) 483-507.
[16] C. Sun, B. Wen, B. Bai, Recent advances in nanoporous graphene membrane for
gas separation and water purification, Sci. Bull. 60 (2015) 1807-1823.
[17] J. Kim, L.J. Cote, J. Huang, Two dimensional soft material: new faces of
graphene oxide, Acc. Chem. Res. 45 (2012) 1356-1364.
[18] G. Liu, W. Jin, N. Xu, Two-dimensional-material membranes: a new family of
high-performance separation membranes, Angew. Chem. Int. Ed. 5 (2016) 2-16.
[19] X. Yang, X. Yang, S. Liu, Molecular dynamics simulation of water transport
through graphene-based nanopores: Flow behavior and structure characteristics,
ACC
EPTE
D M
ANU
SCR
IPT
ACCEPTED MANUSCRIPT
Chinese. J. Chem. Eng. 23 (2015) 1587-1592.
[20] R.R. Nair, H.A. Wu, P.N. Jayaram, I.V. Grigorieva, A.K. Geim, Unimpeded
permeation of water through helium-leak–tight graphene-based membranes, Science
335 (2012) 442-444.
[21] Y. Han, Z. Xu, C. Gao, Ultrathin graphene nanofiltration membrane for water
purification, Adv. Funct. Mater. 23 (2013) 3693-3700.
[22] M. Hu, B. Mi, Enabling graphene oxide nanosheets as water separation
membranes, Environ. Sci. Technol. 47 (2013) 3715-3723.
[23] K. Xu, B. Feng, C. Zhou, A. Huang, Synthesis of highly stable graphene oxide
membranes on polydopamine functionalized supports for seawater desalination, Chem.
Eng. Sci. 146 (2016) 159-165.
[24] N.F.D. Aba, J.Y. Chong, B. Wang, C. Mattevi, K. Li, Graphene oxide membranes
on ceramic hollow fibers – Microstructural stability and nanofiltration performance, J.
Membr. Sci. 484 (2015) 87-94.
[25] X. Chen, G. Liu, H. Zhang, Y. Fan, Fabrication of graphene oxide composite
membranes and their application for pervaporation dehydration of butanol, Chinese. J.
Chem. Eng. 23 (2015) 1102-1109.
[26] H. Huang, Z. Song, N. Wei, L. Shi, Y. Mao, Y. Ying, L. Sun, Z. Xu, X. Peng,
Ultrafast viscous water flow through nanostrand-channelled graphene oxide
membranes, Nat. Commun. 4 (2013) 2979.
[27] K. Huang, G. Liu, Y. Lou, Z. Dong, J. Shen, W. Jin, A graphene oxide membrane
with highly selective molecular separation of aqueous organic solution, Angew. Chem.
Int. Ed. 53 (2014) 6929-6932.
[28] Y.P. Tang, D.R. Paul, T.S. Chung, Free-standing graphene oxide thin films
assembled by a pressurized ultrafiltration method for dehydration of ethanol, J.
Membr. Sci. 458 (2014) 199-208.
[29] G. Li, L. Shi, G. Zeng, Y. Zhang, Y. Sun, Efficient dehydration of the organic
solvents through graphene oxide (GO)/ceramic composite membranes, RSC Adv. 4
(2014) 52012-52015.
[30] W.-S. Hung, Q.-F. An, M. De Guzman, H.-Y. Lin, S.-H. Huang, W.-R. Liu, C.-C.
ACC
EPTE
D M
ANU
SCR
IPT
ACCEPTED MANUSCRIPT
Hu, K.-R. Lee, J.-Y. Lai, Pressure-assisted self-assembly technique for fabricating
composite membranes consisting of highly ordered selective laminate layers of
amphiphilic graphene oxide, Carbon 68 (2014) 670-677.
[31] R.K. Joshi, P. Carbone, F.C. Wang, V.G. Kravets, Y. Su, I.V. Grigorieva, H.A. Wu,
A.K. Geim, R.R. Nair, Precise and ultrafast molecular sieving through graphene oxide
membranes, Science 343 (2014) 752-754.
[32] S.C. O'Hern, M.S. Boutilier, J.C. Idrobo, Y. Song, J. Kong, T. Laoui, M. Atieh, R.
Karnik, Selective ionic transport through tunable subnanometer pores in single-layer
graphene membranes, Nano Lett. 14 (2014) 1234-1241.
[33] H. Li, Z. Song, X. Zhang, Y. Huang, S. Li, Y. Mao, H.J. Ploehn, Y. Bao, M. Yu,
Ultrathin, molecular-sieving graphene oxide membranes for selective hydrogen
separation, Science 342 (2013) 95-98.
[34] H.W. Kim, H.W. Yoon, S.-M. Yoon, B.M. Yoo, B.K. Ahn, Y.H. Cho, H.J. Shin, H.
Yang, U. Paik, S. Kwon, Selective gas transport through few-layered graphene and
graphene oxide membranes, Science 342 (2013) 91-95.
[35] S.P. Koenig, L. Wang, J. Pellegrino, J.S. Bunch, Selective molecular sieving
through porous graphene, Nat. Nanotechnol. 7 (2012) 728-732.
[36] S.C. O’Hern, M.S. Boutilier, J.-C. Idrobo, Y. Song, J. Kong, T. Laoui, M. Atieh,
R. Karnik, Selective ionic transport through tunable subnanometer pores in
single-layer graphene membranes, Nano Lett. 14 (2014) 1234-1241.
[37] H. Kaur, V.K. Bulasara, R.K. Gupta, Preparation of kaolin-based low-cost porous
ceramic supports using different amounts of carbonates, Desalin. Water. Treat. 57
(2016) 15154-15163.
[38] A. Kaiser, S.P. Foghmoes, G. Pećanac, J. Malzbender, C. Chatzichristodoulou,
J.A. Glasscock, D. Ramachandran, D.W. Ni, V. Esposito, M. Søgaard, P.V. Hendriksen,
Design and optimization of porous ceramic supports for asymmetric ceria-based
oxygen transport membranes, J. Membr. Sci. 513 (2016) 85-94.
[39] R. Faiz, M. Fallanza, I. Ortiz, K. Li, Separation of olefin/paraffin gas mixtures
using ceramic hollow fiber membrane contactors, Ind. Eng. Chem. Res. 52 (2013)
7918-7929.
ACC
EPTE
D M
ANU
SCR
IPT
ACCEPTED MANUSCRIPT
[40] Y. Xu, H. Bai, G. Lu, C. Li, G. Shi, Flexible graphene films via the filtration of
water-soluble noncovalent functionalized graphene sheets, J. Am. Chem. Soc. 130
(2008) 5856-5857.
[41] S. Pei, H.-M. Cheng, The reduction of graphene oxide, Carbon 50 (2012)
3210-3228.
[42] A. Lerf, H. He, M. Forster, J. Klinowski, Structure of graphite oxide revisited, J.
Phys. Chem. B 102 (1998) 4477-4482.
[43] H. He, J. Klinowski, M. Forster, A. Lerf, A new structural model for graphite
oxide, Chem. Phys. Lett. 287 (1998) 53-56.
[44] X. Dong, K. Huang, S. Liu, R. Ren, W. Jin, Y.S. Lin, Synthesis of zeolitic
imidazolate framework-78 molecular-sieve membrane: defect formation and
elimination, J. Mater. Chem. 22 (2012) 19222.
[45] X. Gu, Z. Tang, J. Dong, On-stream modification of MFI zeolite membranes for
enhancing hydrogen separation at high temperature, Micropor. Mesopor. Mat 111
(2008) 441-448.
[46] G. Guan, T. Tanaka, K. Kusakabe, K.-I. Sotowa, S. Morooka, Characterization of
AlPO 4-type molecular sieving membranes formed on a porous α-alumina tube, J.
Membr. Sci. 214 (2003) 191-198.
[47] L.M. Robeson, The upper bound revisited, J. Membr. Sci. 320 (2008) 390-400.
ACC
EPTE
D M
ANU
SCR
IPT
ACCEPTED MANUSCRIPT
Highlights
1. Integrated and stable GO membranes were prepared on the ceramic hollow fiber.
2. Gas separation performance of GO membranes was investigated systematically.
3. GO membranes exhibit efficient hydrogen recovery.