Separation and Purification Technology 234 (2020) 116116
Contents lists available at ScienceDirect
Separation and Purification Technology journal homepage: www.elsevier.com/locate/seppur
Fast surface crosslinking ceramic hollow fiber pervaporation composite membrane with outstanding separation performance for isopropanol dehydration
T
Xin Zhang, Meng-Ping Li, Zhi-Hao Huang, Hao Zhang, Wei-Liang Liu, Xin-Ru Xu, Xiao-Hua Ma , ⁎ Zhen-Liang Xu ⁎
Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, Membrane Science and Engineering R&D Lab, Chemical Engineering Research Center, East China University of Science and Technology, 130 Meilong Road, 200237 Shanghai, China
ARTICLE INFO
ABSTRACT
Keywords: Fast surface crosslinking Hollow fiber composite membrane Isopropanol dehydration Arrhenius equation Solution-diffusion model
A facile fast surface crosslinking method was adopted to fabricate ceramic hollow fiber composite membranes with a thin separation layer for outstanding pervaporation (PV) performance. The morphologies, surface chemical compositions and hydrophilicity of the chitosan (CS)/ceramic hollow fiber composite membranes were characterized by field emission scanning electron microscopy (SEM), X-ray photoelectron analysis (XPS), and water contact angle (CA), respectively. The influences of CS concentration, feed composition and temperature on the membrane performances were investigated systematically. The operation time of the surface crosslinking process was several minutes (i.e., 4 min). The thickness of the separation layer of the obtained composite membranes ranged from 322 to 1414 nm, exhibiting excellent separation performance. The Arrhenius active energy (EJ and ED) and the diffusion coefficient (Dw and DIPA) were calculated to theoretically analyze the membrane separation process. The highest PV separation index (PSI) value was 8.2 × 106, indicating that the obtained membranes possessed enormous potential in IPA dehydration.
1. Introduction In order to realize the sustainable development of economy, membrane separation technology was considered as a huge potential technology to treat global environmental issues efficiently [1]. Compared with the traditional separation technology such as distillation, extraction and absorption, pervaporation (PV) was considered as an environmentally friendly and energy saving technology for separation of azeotropic mixtures [2–4]. Membrane itself is the core of the PV separation process. However, the choices of membrane materials (e.g., organic polymer [5,6], molecular sieve [7,8] and inorganic materials [9]) and the modification of membrane materials (e.g., bulk crosslinking and surface modification) were usually key factors to decide the performance of PV membranes. Chitosan (CS) is widely applied in membrane preparation due to its biodegradability, good membrane-formed property, non-toxicity, excellent hydrophilicity and low price [10–13]. However, the pure CS membrane usually possesses poor mechanical strength and low chemical stability. To improve its performance, some modification methods such as bulk crosslinking and surface modification are used to
⁎
modify the pure CS membrane on account of the presence of reactive hydroxyl and amine groups on the CS [14,15]. Although the two methods above-mentioned provided the promising potential, they also exist some serious drawbacks: (i) low membrane flux due to its thicker membrane thickness (i.e., 20–50 μm) caused by excessive crosslinking; and (ii) longer operation times due to low reactive activity of crosslinking agent (i.e., glutaraldehyde), as shown in Table S1. Therefore, the decline of the membrane thickness or the operation time is a potential way to fabricate high-performance membrane with improved flux [16]. An alternative surface crosslinking method similar to interfacial polymerization [17,18] between CS and Trimesoyl chloride (TMC) was adopted to fabricate thinner CS membranes (322–1414 nm) with a higher PV performance. The crosslinking reaction occurs at the interface of CS membrane. The formative dense active surface prevents TMC diffusion into CS membrane matrix for further crosslinking reaction to increase the trans-membrane resistance (see Fig. S1). In addition, the crosslinking method could save considerable operation time due to the rapid reaction between CS and TMC (see Table S1). In this work, the composite membranes with different CS
Corresponding authors. E-mail addresses:
[email protected] (X.-H. Ma),
[email protected] (Z.-L. Xu).
https://doi.org/10.1016/j.seppur.2019.116116 Received 11 February 2019; Received in revised form 20 September 2019; Accepted 20 September 2019 Available online 21 September 2019 1383-5866/ © 2019 Elsevier B.V. All rights reserved.
Separation and Purification Technology 234 (2020) 116116
X. Zhang, et al.
Fig. 1. The cross-section and surface SEM micrographs of (a, b) CS0.5-TMC, (c, d) CS1.0-TMC, (e, f) CS1.5-TMC, and (g, h) CS2.0-TMC composite membranes. The TMC concentration was 0.5 wt%.
concentrations were utilized to investigate the effects of CS concentration, feed composition and temperature on PV performance. The theoretic calculations related to diffusion coefficient (Di), active energies of permeation (EJ) and diffusion (ED) and the heat of sorption (ΔH) were conducted. The obtained membrane exhibited an excellent PV performance for alcohol dehydration, implicating that fast surface crosslinking is a potential method for fabricating high-performance membranes.
≥99.8 wt%) was obtained from Qingdao Benzo Chemical Company, China. Isopropanol (IPA, AR, ≥99.7 wt%), acetic acid (HAc, AR, ≥99.5 wt%) and n-hexane (AR, ≥97.0 wt%) were acquired from Sinopharm Chemical Reagent Co., Ltd. Shanghai, China. The deionized water and ɑ-Al2O3 ceramic support membrane with pore diameter of 0.93 μm [3,19] were fabricated in our lab.
2. Experimental
The CS solution with concentration of 0.5–2.0 wt% was prepared by dissolving CS in the deionized water containing 2.0 wt% of HAc at room temperature. Meanwhile, the testing modules related to ceramic support were fabricated by the process in the paper [6]. The support was immersed in CS solution by dip-coating method for 4 min and the redundant CS solution on the support surface was removed carefully by
2.2. Fabrication of composite membranes
2.1. Materials Chitosan (CS, the deacetylation degree > 80%) was received from Titan Scientific Co., Ltd. Shanghai, China. Trimesoyl chloride (TMC, 2
Separation and Purification Technology 234 (2020) 116116
X. Zhang, et al.
Table 1 Elemental and chemical bonds composition of (a) pure CS1.5 and (b) CS1.5-TMC composite membranes analyzed by XPS. The TMC concentration was 0.5 wt%. Item
Binding energy (eV) Pure CS1.5 1.5 CS -TMC
Atoms percent (%)
Chemical bonds percent (%)
C1s
N1s
O1s
NeC]O
CeO/CeN
CeC/CeH
285.5
399.2
532.2
287.7
286.2
284.6
60.6 66.5
7.0 5.9
32.4 27.6
17.3 15.2
49.5 32.9
33.2 51.9
separation layer by chemical crosslinking of TMC for 4 min. At last, the support with a dense separation layer was placed at 75 ℃ oven for further reaction between CS and TMC for 5 min. The above processes were operated for two times and the differences in the two processes were that the composite membranes were placed upside down during drying process in the oven for obtaining the uniform organic layer on the support surface. As a convenience, the composite membranes were named CSX-TMC where the capital letters X represents the CS concentration. 2.3. Characterizations
Fig. 2. Crosslinking schematic between TMC and CS.
The cross-section and surface morphologies of CSX-TMC composite membranes were observed by field scanning electron microscopy (SEM, Nova NanoSEM 450). The chemical components of membrane surface were analyzed by an X-ray photoelectron analysis (XPS, VG-Miclab Ⅱ, UK). The hydrophilicity was presented by dynamic water contact angle
an annular air knife to guarantee distribution uniformity of CS solution on the ceramic support. After that, the support was once again immersed into the 0.5 wt% TMC- n-hexane solution to fabricate a dense
Fig. 3. XPS wide-scan and C 1s core level of (a) pure CS1.5 and (b) CS1.5-TMC composite membranes. 3
Separation and Purification Technology 234 (2020) 116116
X. Zhang, et al.
Fig. 6. PV performance with different IPA concentration in the feed (70–90 wt %) for the composite membranes with different CS concentration (1.0–2.0 wt %). The TMC concentration and tested temperature were 0.5 wt% and 60 ℃, respectively.
Fig. 4. Dynamic water contact angle of the composite membranes with different CS concentration (0.5–2.0 wt%). The TMC concentration was 0.5 wt%.
J=
=
W A ·t
(1)
P CWP / CIPA F F CW / CIPA
(2)
PSI = J × (
1)
(3)
where W represents the total mass of the collected permeate (g). A and t are the efficient area of composite membranes (m2) and collection time P (h), respectively. The CWP / CIPA represents the mass fraction of water to F IPA in permeate solution and CWF / CIPA denotes that in feed solution. The superscript P and F respectively represent permeate and feed side of membrane, and the subscripts W and IPA represent water and isopropanol, respectively. 3. Results and discussion 3.1. Membrane characterization
Fig. 5. PV performance of the composite membranes with different CS concentration (0.5–2.0 wt%). The TMC concentration was 0.5 wt%. The IPA concentration in the feed and tested temperature were 90 wt% and 60 ℃, respectively.
3.1.1. Effect of CS concentration on the morphologies of the composite membranes Fig. 1 illustrates the SEM images of the cross-section and surface morphologies of the composite membranes. According to the crosssection images, the amount of CS solution adhering on the outside surface of ceramic support, increased with the increase of CS concentration owing to the rise of CS viscosity [21], leading to the thickness of prepared composite membranes increased gradually, ranged from 322 to 1414 nm. Obviously, the membrane thickness is far thinner than that in the available literatures (see Table S1). This will dramatically reduce the trans-membrane resistance and then results in improved flux. Moreover, the voids between ɑ-Al2O3 ceramic particles can be clearly seen in Fig. 1c. A possible explanation is that the certain viscosity of CS solution affects its flow into the voids between ɑ-Al2O3 ceramic particles [3]. From the outside surface images, a smoother surface could be observed on account of the increasing CS concentration.
which were evaluated by contact angle meter (JC2000A, Shanghai Zhong Cheng Digital Equipment Co., Ltd, China) at room temperature. 2.4. Pervaporation experiments The PV experiments were conducted using a self-designed equipment that was described in our previous studies [7,20]. The vacuum pressure in the permeate side of the composite membranes was maintained −0.1 MPa using a pressure self-adjusting vacuum pump (Wade Vacuum Equipment Co., Ltd, Shanghai, China). The test membranes should be immersed in the feed solution for 1 h to guarantee the stability of test device before the PV experiment. After the steady state was obtained, the permeated solution from the downside of membrane was collected in a cold trap using liquid nitrogen. Furthermore, the compositions of feed and permeated solution were estimated by gas chromatography (Techcomp GC7890T, China). The flux (J), separation factor (α) and PV separation index (PSI) of the composite membranes were calculated by the following equations using PV experimental dates.
3.1.2. Chemical properties of the composite membranes The crosslinking reaction between CS and TMC is presented in Fig. 2 and the variation in surface composition of the pure CS1.5 membrane and CS1.5-TMC membrane is shown in Fig. 3 and Table 1. As shown in Fig. 3, three peaks at binding energy of 285.5, 399.2 and 532.2 eV were observed from the wide-scan spectra, which represented C 1s, N 1s and O 1s region, respectively [22,23]. The corresponding atom content 4
Separation and Purification Technology 234 (2020) 116116
X. Zhang, et al.
Table 2 Diffusion coefficient of water and IPA for the composite membranes at different IPA concentration in feed. IPA in feed (wt%)
Dw × 108 (cm2/s)
DIPA × 1010 (cm2/s)
CS1.0-TMC
CS1.5-TMC
CS2.0-TMC
CS1.0-TMC
CS1.5-TMC
CS2.0-TMC
90 85 80 75 70
5.32 5.89 6.42 6.90 6.36
2.98 3.40 4.67 4.98 5.96
3.13 3.54 4.68 5.45 6.25
1.20 1.77 2.74 4.48 5.48
0.06 0.11 0.54 0.92 2.06
0.03 0.10 0.43 0.56 1.62
IPA in feed (wt%)
Dw × 108 (cm2/s)
DIPA × 1010 (cm2/s)
M1
M1-2
M1-4
M1
M1-2
M1-4
90 85 75
5.65 6.14 7.90
10.53 11.02 13.01
12.91 13.82 17.71
6.10 11.12 58.61
4.64 10.10 49.91
11.42 22.31 68.80
IPA in feed (wt%)
Dw × 108 (cm2/s)
90 80 70
This work
Ref. [15]
DIPA × 1010 (cm2/s)
M2-1
M2-2
M2-4
M2-1
M2-2
M2-4
11.40 11.20 10.30
8.40 9.83 8.31
5.90 6.06 5.73
0.79 1.49 4.36
0.30 0.96 2.59
0.10 0.40 0.65
Ref. [29]
Note: pure CS membrane (M1) and its crosslinked membranes in Ref. [15]: (M1-2) 0.8 wt%; (M1-4) 1.6 wt% of TGDMP; pure CS membrane (M2-1) and its crosslinked membranes in Ref. [29]: (M2-2) 10 wt% ETMS; (M2-4) 40 wt% of ETMS; TGDMP: Ti[(O3PCH2)2NCH2COOH]; ETMS:2-(3,4-epoxycyclohexyl) ethyltrimethoxysilane.
Fig. 7. PV performance at operating temperature (40–70 ℃) for the composite membranes with different CS concentration. The TMC concentration and the feed IPA concentration were 0.5 wt% and 90 wt%, respectively.
Fig. 8. Variation of ln (D) with temperature for CS1.0-TMC, CS1.5-TMC and CS2.0-TMC composite membranes at 90 wt% IPA in feed.
listed in Table 1 indicates that the C 1s atom content increases while the N 1s and O 1s atom contents decrease after the CS is cross-linked by TMC monomers. The three peaks of the C1 score-level spectrum appeared at binding energy of 284.6, 286.2, and 287.7 eV represent CeC/ CeH, CeO/CeN and NeC]O chemical bonds, respectively [24]. A remarkable phenomenon in the Table 1 is that the peak area of CeO/ CeN bonds decreased significantly, but the peak area of CeC/CeH increased dramatically. Moreover, the FTIR spectra of pure CS and the crosslinked membranes are presented in Fig. S1. Compared with the pure CS membranes, the absorption band of –OH narrows and the peak position of C]O groups of the crosslinked membranes presents obvious redshift phenomena. All the phenomena mentioned above suggested that the reaction between TMC and CS was successfully occurred (see Fig. 2).
membranes was measured by the dynamic water contact angle. As shown in Fig. 4, it is obvious that the initial water contact angle of the composite membranes cross-linked by TMC was smaller than that of the pure CS1.5 membrane. The water droplet completely penetrated into the cross-linked CS composite membranes with the prolonging of time. There was no doubt that the cross-linked CS by TMC was more hydrophilic than the pure CS which was beneficial to the improvement of membrane flux. In addition, the initial water contact angle increased gradually with the CS concentration increased by comparison among the cross-linked composite membranes, which revealed that the hydrophilicity of the composite membranes declined with the increased CS concentration. A possible explanation for the phenomenon was that a smoother and denser membrane was prepared on the ceramic support with the increase of CS concentration (see Fig. 1).
3.1.3. Hydrophilicity of the outside surface of composite membranes The water contact angle is an important parameter related to the hydrophilicity of the material [25]. The hydrophilicity of the composite 5
Separation and Purification Technology 234 (2020) 116116
X. Zhang, et al.
resulting in sharply increased separation factor. For instance, the CS2.0TMC composite membrane had separation factor of nearly 10000. Correspondingly, the flux decreased but was still higher than 640 g/ m2h. 3.2.2. Effect of IPA concentration in feed Fig. 6 demonstrates the effect of the IPA concentration in feed on the PV flux and separation factor for CS1.0-TMC, CS1.5-TMC and CS2.0TMC composite membranes at 60 ℃. As illustrated in Fig. 6, the increase of composite membranes flux is almost linearly associated with the increase of water concentration in the feed while the separation factor decreases. The above phenomena were explained by the following reasons: (i) the increase of water driving force due to increased water partial pressure with increased water content in feed [20]; (ii) the increase of collision efficiency (CE) between the membrane and the water molecules due to increase in number of water molecules in feed. Specifically, the CE can be described by the following equation:
CE = 1.0
Fig. 9. Variation of ln (J) with temperature for CS -TMC, CS CS2.0-TMC composite membranes at 90 wt% IPA in feed.
1.5
-TMC and
CS1.0-TMC
CS1.5-TMC
CS2.0-TMC
EJ ED EJw EJIPA ΔH
19.9 19.9 20.6 1.5 0.0
23.1 23.1 23.2 1.3 0.0
24.5 24.5 24.5 10.3 0.0
Parameters (KJ/mol)
M1
M1-2
M1-4
EJ ED EJw EJIPA ΔH1
20.0 19.7 19.4 45.5 0.3
4.4 4.1 3.9 34.4 0.3
3.0 2.8 2.1 27.4 0.2
Parameters (KJ/mol)
M2-1
M2-2
M2-4
EJ ED EJw EJIPA ΔH2
21.6 22.6 21.0 43.2 −1.0
23.1 23.8 23.4 51.4 −0.7
33.3 33.5 33.6 66.2 −0.2
(4)
where NW represents the number of collisions between water molecules and membrane surface, the NIPA stands for the number the collision between IPA molecules and membrane surface. Obviously, the increase of collision efficiency as increased water concentration in feed is benefit for water movement across the membrane. The major reason is enhanced interactions between water molecules and hydrophilic groups such as NH2, NH3+, CO-NH, and OH on the membrane surface.
Table 3 Active energies for permeation and diffusion at 90 wt% IPA in feed. Parameters (KJ/mol)
NW NW + NIPA
This work
3.2.3. Theoretic calculation of diffusion coefficient The separation process of feed mixtures is evaluated by the solutiondiffusion model which included three steps (adsorption, diffusion, and desorption) [26–28]. The calculation of the diffusion coefficient was very important to investigate the mechanism of the molecular transport of water and IPA in this study. The flux of the composite membranes was interpreted by the following the same form equation [29–32] as Fick’s law:
Ref. [15]
Ji = Ref. [29]
Di dci dx
(5) 2
where Ji is PV flux of IPA or water, respectively (Kg/m h), C stands for the mass-volume concentration on the downstream of the membrane (Kg/m3), x represents the thickness of the separation layer and the D symbolizes the diffusion coefficient. The subscript i represents IPA or water. When the diffusion coefficient is assumed to be independent of concentration, integrating the above Eq. (5) over the membrane thickness (l ) gives:
Note: pure CS membrane (M1) and its crosslinked membranes in Ref. [15]: (M12) 0.8 wt%; (M1-4) 1.6 wt% of TGDMP; pure CS membrane (M2-1) and its crosslinked membranes in Ref. [29]: (M2-2) 10 wt% ETMS; (M2-4) 40 wt% of ETMS; TGDMP: Ti[(O3PCH2)2NCH2COOH]; ETMS:2-(3,4-epoxycyclohexyl) ethyltrimethoxysilane.
Ji = Di
cif
cip l
(6)
where l stands for the thickness of the separation layer which is measured by the SEM images in Fig. 1 and the PV flux (Ji) is shown in Table S3. The cif and cip are the mass-volume concentration of solution in feed and permeate, respectively. The diffusion coefficient (Di ) obtained by calculation is shown in Table 2 which represented diffusion rate of IPA and water molecules in membrane matrix. The calculated diffusion coefficients of water and IPA are illustrated in Table 2. It is clear that the diffusion coefficient of water was two to four orders magnitude higher than that of IPA, robustly demonstrating that the obtained composite membranes possessed a high selectivity for IPA and water. The diffusion coefficient of the CS1.0-TMC composite membrane was also higher than that of other composite membranes, which perfect explained why the CS1.0-TMC composite membrane possessed higher flux. The diffusion coefficients of IPA reported in literatures were also calculated and used for comparison. It is obvious that the calculated diffusion coefficients of IPA in ref. [15] were much higher than those in
3.2. PV experiment and theoretic analysis 3.2.1. Effect of CS concentration Fig. 5 and Table S2 show the effect of CS concentration on the membrane performance by dehydration of 90 wt% IPA-water at 60 ℃. The flux of the composite membranes decreased while the separation factor increased with the increasing CS concentration. One possible explanation for this result is that the membrane resistance for solution penetration increased gradually because the membrane thickness continues to increase with increasing CS concentration (see Fig. 1). In addition, the separation factor of composite membrane with 0.5 wt% CS concentration was merely 10.7 due to the existence of some defects. This is mainly because it is hard to fabricate a defect-free thin separation layer (322 nm in Fig. 1a) on a ceramic hollow fiber membrane support with a pore diameter of 0.93 μm. The defects reduced gradually with increased CS concentration as well as membrane thickness, 6
Separation and Purification Technology 234 (2020) 116116
X. Zhang, et al.
Table 4 PV performance comparison with those of the available PV composite membranes in literatures. Membrane material 2.0
CS -TMC CS2.0-TMC CS1.0-TMC TGDMP incorporated Membranes Chitosan/P(AANa-co-SSNa) QP4VP/CMC-Na Matrimid (R)/zeolite 4A SA/CS wrapped MWCNTs Polybenzoxazole (PBO) PVA/PDDA/CMC-Na Poly(vinyl alcohol) Matrimid (R)/MgO Poly(vinyl alcohol)/TMC MPDSA-TMC Chitosan modified polybenzimidazole (PBI) PDDA/PSS (PEC + )/PDMC/CMCNa HPEI-TMC Polybenzimidazole (PBI)/ZIF-8 P84/ZIF-90/sulfonated polyethersulfone
mass% of IPA in feed
Operation temperature (℃)
Flux (g/m2h)
Separation factor
PSI (×105 g/m2h)
Reference
90 90 70 90 90 90 90 90 90 90 90 82 80 70 70 90 85 85 85
70 60 60 30 40 60 30 30 80 70 40 100 60 25 70 60 50 60 60
908 640 9102 74 1250 1490 159 218 135 1350 35 630 320 1669 250 1180 1282 246 109
8993 9634 116 1050 1490 > 2000 890 6420 140 1000 3452 700 400 775 115 1010 624 310 > 5000
81.6 61.7 10.5 0.8 18.6 29.8 1.4 14.0 0.2 13.5 1.2 4.4 1.3 12.9 0.3 11.9 8.0 0.8 5.5
This work
this work, but these membranes had poor separation performance (see Table S4). A possible explanation is that the thickness of the membrane in Ref. [15] and 29 (∼40 μm) was much thicker than that in this work (322–1414 nm) since diffusion coefficient (D) is proportional to membrane thickness (l) (see formula (6)). This indicates that the thickness of the membrane significantly influences the performance of the membrane.
the partial flux of water is more sensitive to the temperature than the partial flux of IPA. That also explains why the separation factor of the composite membranes increases gradually with the increase of the temperature at first. In addition, the heat of sorption was calculated using the values of EJ and ED by the following equation.
H = EJ
4. Conclusion High-performance PV composite membranes were successful fabricated on the ɑ-Al2O3 ceramic hollow fiber membrane support by a facile surface crosslinking method. The operation time could be reduced to several minutes. The influence of several variables (e.g., CS concentration, temperature, and IPA concentration in feed) on the membrane performance was systematically investigated. The XPS results indicated that the surface CS on the ceramic support was successful cross-linked by TMC. The membrane containing 2.0 wt% CS possessed the highest separation factor of 9634 with membrane flux of 640 g/m2h at 60 ℃ for 85 wt% IPA in the feed. The CS2.0-TMC composite membrane showed the largest PSI value of 8.2 × 106 which suggested that the fabricated composite membrane possessed potential in IPA dehydration. Through theoretical calculation, we found that both Henry’s model and Langmuir’s model combine to determine the PV performance of composite membranes.
(7)
where the K represents the membrane flux (J), or diffusion coefficient (D). K0 represents pre-exponential factor (J0 or D0) which is a constant value, EX stands for the active energy of permeation or diffusion, R is the molar gas constant and T is the thermodynamic temperature. For convenience, the active energy was also usually calculated by the other form of Arrhenius equation.
InK =
EX + InK 0 RT
(9)
3.2.6. Separation performance comparison with the available literatures The PV performance of the fabricated composite membranes are compared with the available literatures in Table 4. The results indicated the fabricated composite membranes possessed outstanding PV performance.
3.2.5. Theoretic calculation of activation energy The active energy of permeation and diffusion can be calculated by the following Arrhenius equation.
EX RT
ED
The ΔH was a comprehensive parameter which contained the contribution of Henry’s and Langmuir’s mode. Compared with other literatures in Table 3, the value of ΔH was approximately equal to zero which illustrated that both Henry’s model and Langmuir’s model combine to determine the PV performance of composite membranes.
3.2.4. Effect of temperature The flux and separation factor of the composite membranes at different temperature are presented in Fig. 7 and Table S5. It was found that the permeation flux was almost linear with the operating temperature. The separation factor increased gradually until the operation temperature reached 60 ℃ and decreased slightly when the operation temperature was increased from 60 ℃ to 70 ℃. Similar to the effects of IPA concentration in feed, the collision efficiency between the composite membranes and the water molecules increased because water and IPA molecular acquired more momentum with increase of the operating temperature. In addition, the effect of activation energies on diffusion and permeation should be considered.
K = K 0 exp
[15] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47]
(8)
The fitting lines related to the active energy of D and J are presented in Figs. 8 and 9, respectively. The calculated active energies for diffusion and permeation are presented in Table 3. From this table, the values of EJ and ED increased with increasing CS concentration. This indicated that the more active energy was acquired for permeation and diffusion of IPA and water when the composite membranes were prepared using higher concentration of CS. Furthermore, the value of EJIPA is far less than that of EJW (see Fig. S2 and Table 3), which indicates that
Acknowledgment The authors gratefully acknowledge the research funding provided by Hong Kong Scholars Program (No. XJ2015015), National Natural Science Foundation of China (21176067 and 21406060), Fundamental Research Funds for the Central Universities (WA1514305) and China Postdoctoral Science Foundation (2016M601527). 7
Separation and Purification Technology 234 (2020) 116116
X. Zhang, et al.
Appendix A. Supplementary material [24]
Supplementary data to this article can be found online at https:// doi.org/10.1016/j.seppur.2019.116116.
[25]
References [26]
[1] Y.K. Ong, G.M. Shi, N.L. Le, Y.P. Tang, J. Zuo, S.P. Nunes, T.S. Chung, Recent membrane development for pervaporation processes, Prog. Polym. Sci. 57 (2016) 1–31. [2] P.D. Chapman, T. Oliveira, A.G. Livingston, K. Li, Membranes for the dehydration of solvents by pervaporation, J. Membr. Sci. 318 (2008) 5–37. [3] X. Zhang, M. Wang, C.H. Ji, X.R. Xu, X.H. Ma, Z.L. Xu, Multilayer assembled CSPSS/ceramic hollow fiber membranes for pervaporation dehydration, Sep. Purif. Technol. 203 (2018) 84–92. [4] J. Zuo, G.M. Shi, S. Wei, T.S. Chung, The development of novel nexar block copolymer/ultem composite membranes for C2–C4 alcohols dehydration via pervaporation, ACS Appl. Mat. Interfaces 6 (2014) 13874–13883. [5] H.R. Xie, C.H. Ji, S.M. Xue, Z.L. Xu, H. Yang, X.H. Ma, Enhanced pervaporation performance of SA-PFSA/ceramic hybrid membranes for ethanol dehydration, Sep. Purif. Technol. 206 (2018) 218–225. [6] C.H. Ji, S.M. Xue, Z.L. Xu, Novel swelling-resistant sodium alginate membrane branching modified by glycogen for highly aqueous ethanol solution pervaporation, ACS Appl. Mat. Interfaces 8 (2016) 27243–27253. [7] Y. Cao, M. Wang, Z.L. Xu, X.H. Ma, S.M. Xue, A novel seeding method of interfacial polymerization-assisted dip coating for the preparation of zeolite NaA membranes on ceramic hollow fiber supports, ACS Appl. Mat. Interfaces 8 (2016) 25386–25395. [8] M. Wang, Y. Cao, Y.X. Li, S.M. Xue, Z.L. Xu, Preparation of MFI zeolite membranes on coarse macropore stainless steel hollow fibers for the recovery of bioalcohols, RSC Adv. 6 (2016) 109936–109944. [9] Y. Cao, Y.X. Li, M. Wang, Z.L. Xu, Y.M. Wei, B.J. Shen, K.K. Zhu, High-flux NaA zeolite pervaporation membranes dynamically synthesized on the alumina hollow fiber inner-surface in a continuous flow system, J. Membr. Sci. 570 (2019) 445–454. [10] A.M. Sajjan, H.G. Premakshi, M.Y. Kariduraganavar, Synthesis and characterization of GTMAC grafted chitosan membranes for the dehydration of low water content isopropanol by pervaporation, J. Ind. Eng. Chem. 25 (2015) 151–161. [11] Q.G. Zhang, W.W. Hu, A.M. Zhu, Q.L. Liu, UV-crosslinked chitosan/polyvinylpyrrolidone blended membranes for pervaporation, RSC Adv. 3 (2013) 1855–1861. [12] Q.W. Yeang, S.H.S. Zein, A. Sulong, S.H. Tan, Comparison of the pervaporation performance of various types of carbon nanotube-based nanocomposites in the dehydration of acetone, Sep. Purif. Technol. 107 (2013) 252–263. [13] H. Wu, X.S. Li, C.H. Zhao, X.H. Shen, Z.Y. Jiang, X.F. Wang, Chitosan/sulfonated polyethersulfone-polyethersulfone (CS/SPES-PES) composite membranes for pervaporative dehydration of ethanol, Ind. Eng. Chem. Res. 52 (2013) 5772–5780. [14] J. Wang, W.Y. Zhang, W.X. Li, W.H. Xing, Preparation and characterization of chitosan-poly (vinyl alcohol)/polyvinylidene fluoride hollow fiber composite membranes for pervaporation dehydration of isopropanol, Korean J. Chem. Eng. 32 (2015) 1369–1376. [15] H.G. Premakshi, A.M. Sajjan, M.Y. Kariduraganavar, Development of pervaporation membranes using chitosan and titanium glycine-N, N-dimethylphosphonate for dehydration of isopropanol, J. Mater. Chem. A 3 (2015) 3952–3961. [16] G.M. Shi, T.S. Chung, Thin film composite membranes on ceramic for pervaporation dehydration of isopropanol, J. Membr. Sci. 448 (2013) 34–43. [17] X.H. Ma, Z.K. Yao, Z. Yang, H. Guo, Z.L. Xu, C.Y.Y. Tang, M. Elimelech, Nanofoaming of polyamide desalination membranes to tune permeability and selectivity, Environ. Sci. Tech. Let. 5 (2018) 123–130. [18] X.H. Ma, Z. Yang, Z.K. Yao, H. Guo, Z.L. Xu, C.Y.Y. Tang, Interfacial polymerization with electrosprayed microdroplets: toward controllable and ultrathin polyamide membranes, Environ. Sci. Tech. Let. 5 (2018) 117–122. [19] L.F. Han, Z.L. Xu, Y. Cao, Y.M. Wei, H.T. Xu, Preparation, characterization and permeation property of Al2O3, Al2O3-SiO2 and Al2O3-kaolin hollow fiber membranes, J. Membr. Sci. 372 (2011) 154–164. [20] X.H. Ma, H.X. Zhang, S.W. Gu, Y. Cao, X. Wen, Z.L. Xu, Process optimization and modeling of membrane reactor using self-sufficient catalysis and separation of difunctional ceramic composite membrane to produce methyl laurate, Sep. Purif. Technol. 132 (2014) 370–377. [21] J. Desbrieres, Viscosity of semiflexible chitosan solutions: Influence of concentration, temperature, and role of intermolecular interactions, Biomacromolecules 3 (2002) 342–349. [22] S.M. Xue, C.H. Ji, Z.L. Xu, Y.J. Tang, R.H. Li, Chlorine resistant TFN nanofiltration membrane incorporated with octadecylamine-grafted GO and fluorine-containing monomer, J. Membr. Sci. 545 (2018) 185–195. [23] S.M. Xue, Z.L. Xu, Y.J. Tang, C.H. Ji, Polypiperazine-amide nanofiltration
[27] [28] [29]
[30] [31] [32] [33] [34] [35] [36]
[37] [38] [39] [40] [41] [42]
[43] [44] [45] [46] [47]
8
membrane modified by different functionalized multiwalled carbon nanotubes (MWCNTs), ACS Appl. Mat. Interfaces 8 (2016) 19135–19144. Y.J. Tang, Z.L. Xu, S.M. Xue, Y.M. Wei, H. Yang, Improving the chlorine-tolerant ability of polypiperazine-amide nanofiltration membrane by adding NH2-PEG-NH2 in the aqueous phase, J. Membr. Sci. 538 (2017) 9–17. S. Al-Gharabli, E. Hamad, M. Saket, Z. Abu El-Rub, H. Arafat, W. Kujawski, J. Kujawa, Advanced material-ordered nanotubular ceramic membranes covalently capped with single-wall carbon nanotubes, Materials 11 (2018) 739. A.V. Klinov, R.R. Akberov, A.R. Fazlyev, M.I. Farakhov, Experimental investigation and modeling through using the solution-diffusion concept of pervaporation dehydration of ethanol and isopropanol by ceramic membranes HybSi, J. Membr. Sci. 524 (2017) 321–333. P. Schaetzel, R. Bouallouche, H.A. Amar, Q.T. Nguyen, B. Riffault, S. Marais, Mass transfer in pervaporation: the key component approximation for the solution-diffusion model, Desalination 251 (2010) 161–166. J.G. Wijmans, The role of permeant molar volume in the solution-diffusion model transport equations, J. Membr. Sci. 237 (2004) 39–50. P.S. Rachipudi, A.A. Kittur, A.M. Sajjan, M.Y. Kariduraganavar, Synthesis and characterization of hybrid membranes using chitosan and 2-(3,4-epoxycyclohexyl) ethyltrimethoxysilane for pervaporation dehydration of isopropanol, J. Membr. Sci. 441 (2013) 83–92. J.G. Wijmans, R.W. Baker, The solution-diffusion model: a review, J. Membr. Sci. 107 (1995) 1–21. J.G. Wijmans, R.W. Baker, The Solution-Diffusion Model: A Unified Approach to Membrane Permeation. Materials Science of Membranes for Gas and Vapor Separation, John Wiley & Sons Ltd, 2006. J.G. Varghese, A.A. Kittur, P.S. Rachipudi, M.Y. Kariduraganavar, Synthesis, characterization and pervaporation performance of chitosan-g-polyaniline membranes for the dehydration of isopropanol, J. Membr. Sci. 364 (2010) 111–121. X.S. Wang, Q.F. An, Q. Zhao, K.R. Lee, J.W. Qian, C.J. Gao, Preparation and pervaporation characteristics of novel polyelectrolyte complex membranes containing dual anionic groups, J. Membr. Sci. 415 (2012) 145–152. T. Liu, Q.F. An, Q. Zhao, K.R. Lee, B.K. Zhu, J.W. Qian, C.J. Gao, Preparation and characterization of polyelectrolyte complex membranes bearing alkyl side chains for the pervaporation dehydration of alcohols, J. Membr. Sci. 429 (2013) 181–189. O. Bakhtiari, S. Mosleh, T. Khosravi, T. Mohammadi, Mixed matrix membranes for pervaporative separation of isopropanol/water mixtures, Desalin. Water Treat. 41 (2012) 45–52. A.M. Sajjan, B.K.J. Kumar, A.A. Kittur, M.Y. Kariduraganavar, Novel approach for the development of pervaporation membranes using sodium alginate and chitosanwrapped multiwalled carbon nanotubes for the dehydration of isopropanol, J. Membr. Sci. 425 (2013) 77–88. Y.K. Ong, H. Wang, T.S. Chung, A prospective study on the application of thermally rearranged acetate-containing polyimide membranes in dehydration of biofuels via pervaporation, Chem. Eng. Sci. 79 (2012) 41–53. Q. Zhao, J.W. Qian, Q.F. An, M.H. Zhu, M.J. Yin, Z.W. Sun, Poly(vinyl alcohol)/ polyelectrolyte complex blend membrane for pervaporation dehydration of isopropanol, J. Membr. Sci. 343 (2009) 53–61. P.S. Rachipudi, M.Y. Kariduraganavar, A.A. Kittur, A.M. Sajjan, Synthesis and characterization of sulfonated-poly(vinyl alcohol) membranes for the pervaporation dehydration of isopropanol, J. Membr. Sci. 383 (2011) 224–234. L.Y. Jiang, T.S. Chung, R. Rajagopalan, Matrimid (R)/MgO mixed matrix membranes for pervaporation, AIChE J. 53 (2007) 1745–1757. S.D. Xiao, R.Y.M. Huang, X.S. Feng, Preparation and properties of trimesoyl chloride crosslinked poly(vinyl alcohol) membranes for pervaporation dehydration of isopropanol, J. Membr. Sci. 286 (2006) 245–254. S.T. Kao, S.H. Huang, D.J. Liaw, W.C. Chao, C.C. Hu, C.L. Li, D.M. Wang, K.R. Lee, J.Y. Lai, Interfacially polymerized thin-film composite polyamide membrane: positron annihilation spectroscopic study, characterization and pervaporation performance, Polym. J. 42 (2010) 242–248. Y.J. Han, K.H. Wang, J.Y. Lai, Y.L. Liu, Hydrophilic chitosan-modified polybenzoimidazole membranes for pervaporation dehydration of isopropanol aqueous solutions, J. Membr. Sci. 463 (2014) 17–23. Q. Zhao, J.W. Qian, Q.F. An, Z.W. Sun, Layer-by-layer self-assembly of polyelectrolyte complexes and their multilayer films for pervaporation dehydration of isopropanol, J. Membr. Sci. 346 (2010) 335–343. J. Zuo, Y. Wang, S.P. Sun, T.S. Chung, Molecular design of thin film composite (TFC) hollow fiber membranes for isopropanol dehydration via pervaporation, J. Membr. Sci. 405 (2012) 123–133. G.M. Shi, T.X. Yang, T.S. Chung, Polybenzimidazole (PBI)/zeolitic imidazolate frameworks (ZIF-8) mixed matrix membranes for pervaporation dehydration of alcohols, J. Membr. Sci. 415 (2012) 577–586. D. Hua, Y.K. Ong, Y. Wang, T.X. Yang, T.S. Chung, ZIF-90/1384 mixed matrix membranes for pervaporation dehydration of isopropanol, J. Membr. Sci. 453 (2014) 155–167.