Ultrahigh Desalinization Performance of Asymmetric Flow-Electrode

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Ultrahigh desalinization performance of asymmetric flow-electrode capacitive deionization device with an improved operation voltage of 1.8 V Xingtao Xu, Miao Wang, Yong Liu, Ting Lu, and Likun Pan ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.6b01212 • Publication Date (Web): 23 Nov 2016 Downloaded from http://pubs.acs.org on November 25, 2016

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ACS Sustainable Chemistry & Engineering

Ultrahigh desalinization performance of asymmetric flow-electrode capacitive deionization device with an improved operation voltage of 1.8 V

Xingtao Xu, Miao Wang, Yong Liu, Ting Lu and Likun Pan∗

Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, East China Normal University, 3663 N. Zhongshan Rd., Shanghai 200062 China E-mail: [email protected] (Xingtao Xu); [email protected] (Miao Wang); [email protected] (Yong Liu); [email protected] (Ting Lu) * Corresponding author. Tel: +86 21 62234132; Fax: +86 21 62234321. E-mail: [email protected] (Likun Pan)

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Abstract Flow-electrode

capacitive

deionization

(FCDI)

is

an

emerging

desalinization technology for high-concentration saline water treatment. However, in practical cases the operation voltage of FCDI is usually limited by the decomposition potential of water (1.23 V), which does harm the desalinization performance of FCDI. In order to address this issue, here for the first time we propose a novel asymmetric FCDI (AFCDI) device by using activated carbon (AC)/MnO2 suspension as positive electrode and AC suspension as negative electrode. In AFCDI, the operation voltage can be improved to be 1.8 V, and a high salt removal efficiency of 78% is achieved in 0.1 M NaCl solution within 2 h, much higher than that for conventional FCDI (59%). To the best of knowledge, this value is also much higher than those for other FCDI devices reported previously. The present work may provide a promising high-performance desalinization device for high-concentration saline water treatment.

Keywords: Asymmetric flow-electrode capacitive deionization; Operation voltage; High-concentration saline water treatment; Desalinization

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1. Introduction Nowadays, the shortage of clean water resources has become one of the most serious challenges with the increasing requirement of household, industry and agriculture application.1-6 Capacitive deionization (CDI), also known as electrosorption, has been recently receiving great interests in desalination field due to its lower energy consumption and environmental friendliness compared with conventional desalination technologies.7-11 This emerging technology is realized by adsorbing ions into the electric double layers (EDL) formed at the interface between the electrode and the solution when a low direct current (DC) potential (normally ≤ 1.2 V) is applied. Recent advances in CDI have been focused on the developments of CDI theory,12-16 experiment methods,17-22 system architectures,23-27 and electrode materials.6, 28-36 Despite the progresses achieved by now, most of the works are restricted in the solution with a low or moderate ion concentration, which cannot meet the demand of practical applications. To solve this problem, Jeon et al presented a new CDI system, called flow-electrode CDI (FCDI), which was operated by applying active material suspension as flow-electrode that had been explored in flowable supercapacitor by Gogotsi’s group.37 This approach realized continuous operation of single-pass CDI system and exhibited high salt removal efficiency (95%) in concentrated NaCl solution (32.1 g L-1). Within the concept of FCDI, various techniques were developed, such as the

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exploration of new FCDI architecture and energy generation in FCDI.38-42 In these cases, the operation voltages are typically limited to below 1.23 V owing to water decomposition at higher voltages, resulting in poor desalinization performance. In order to address this issue, here for the first time we propose a novel asymmetric FCDI (AFCDI) device by using activated carbon (AC)/MnO2 suspension as positive electrode and AC suspension as negative electrode (Figure 1). In this system, an improved operation voltage of 1.8 V is achieved due to the expanded potential window between positively polarized AC/MnO2 electrode and negatively polarized AC electrode.43-44 Benefiting from the improved operation voltage, the salt electrosorption of AFCDI device reaches a high salt removal efficiency of 78% in 0.1 M NaCl solution within 2 h, much higher than that for conventional FCDI (59%).

Figure 1. Schematic representation of AFCDI device.

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2. Experimental section

2.1 Material synthesis The AC/MnO2 used in this study was synthesized as reported previously.43 In brief, AC (Fuzhou Huanyi Carbon Company) was used as both of the sacrificial reductant and matrix. Nano-structured MnO2 was deposited on the carbon matrix via the redox reaction between AC and KMnO4 in acid solution. Both the AC and AC/MnO2 were characterized by field emission scanning electron microscopy (FESEM, JEOL JSM-LV5610), X-ray powder diffractometer (XRD, Rigaku D/Max2550, Cu Kα radiation) and N2 adsorption-desorption isotherm (Micromeritics Instrument Corporation, TriStar II 3020) without further pre-treatment. The specific surface areas of the samples were evaluated based on the Brunauer-Emmett-Teller (BET) model by using the adsorption branches in the relative pressure (P/P0) range of 0.05-0.5. The pore volumes and pore size distributions were calculated from the adsorption branches of isotherms based on the density functional theory method.

2.2 Electrochemical characterization To investigate the electrochemical performances of AC and AC/MnO2, film working electrodes were fabricated as follows. In detail, the active materials, carbon black and polyvinyl alcohol, with a weight ratio of 80: 10: 10, were homogeneously mixed in deionized water at room temperature to get the electrode slurries. Then, the electrode slurries were uniformly coated on

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graphite papers through a casting method. Finally, the electrodes were dried at 80 °C under vacuum for 12 h. Cyclic voltammetry (CV) was carried out on an Autolab PGSTAT 302 N electrochemical workstation in 1 M NaCl solution. The platinum foil and saturated calomel electrode (SCE) were used as counter and reference electrodes, respectively. The specific capacitance (Cs, F g-1) was calculated from the CV curves according to the following equation:

Cs =

∫ idV 2 × m × ∆V × S

(1)

where ∫idV is the integrated area of the CV curve (W), m is the active material mass of one electrode (g), ∆V is the window voltage (V), and S is the scan rate (mV s-1).

2.3 Desalinization performance test Figure S1 (Supporting Information) shows the lab-scale setup of typical AFCDI structure. Flow-electrodes flow through the current and electrode compartments carved from graphite plates (10 mm, Qingdao Runhai Graphite Company) with a flow area in the dimensions (L×W×H) of 7×4×0.3 cm. Cation exchange membrane (CEM, Neosepta® CMX, Japan) and anion exchange membrane (AEM, Neosepta® AMX, Japan) were used with thicknesses of 170 µm and 140 µm, respectively. In a typical AFCDI system, flow-electrodes (50 mL in volume) composed of AC (negative electrode, 3.5 wt%) or AC/MnO2 (positive electrode, 4.13 wt%), carbon black (1.5 wt%) and NaCl aqueous solutions (0.1 M) were

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recycled at a flow rate of 100 mL min-1 using peristaltic pumps. The salt water made of NaCl (0.1 M, 50 mL) was recycled at a flow rate of 50 mL min-1. A constant voltage of 1.8 V was supplied using DC power supply. The variation of NaCl concentration was monitored and measured at the outlet of the unit cell using a conductivity meter (DJS-10C, Precision & Scientific Instrument). For comparison, a conventional FCDI system with flow-electrodes (50 mL in volume) composed of AC (3.5 wt%), carbon black (1.5 wt%) and NaCl aqueous solutions (0.1 M) was conducted at a flow rate of 100 mL min-1 and a constant voltage of 1.2 V. The salt removal efficiency (η, %) and mean electrosorption rate (v, mg g-1 min-1) can be calculated as following:

η=

v=

( C0 -C ) ×100%

(2)

C0

( C0 -C ) ×V m×t

(3)

where C0 and C is the initial and final NaCl concentration (mg L-1), V is the volume of NaCl solution (L), m is the mass of the active materials (g) and t is the electrosorption time (min).

3. Results and discussion

3.1 Characterization of materials

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Figure 2 shows the FESEM images of AC and AC/MnO2. It can be seen that AC exhibits various sized particles with smooth surfaces (Figure 2a, b), while AC/MnO2 exhibits a flower-shape structure with sheet-like MnO2 attached on the surface of AC (Figure 2c, d). The diameter of AC/MnO2 is about 1 µm. The structures of AC and AC/MnO2 were further investigated by XRD measurements, as shown in Figure 3. Clearly, AC exhibits a broad peak centered at ~44°, indicating its amorphous structure. In contrast, AC/MnO2 exhibits sharp peaks centered at 37.5°, and 65.1°, which are assigned to the (310) and (002) planes of the tetragonal α-type MnO2 phase (JCPDS 44-0141), respectively. These results indicate that MnO2 is anchored on the surface of AC successfully via a simple redox reaction with a moderate preparation condition, which is beneficial for further studies and practical application.

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Figure 2. FESEM images of (a, b) AC and (c, d) AC/MnO2 particles.

Figure 3. XRD patterns of AC and AC/MnO2 particles. The porosity of AC and AC/MnO2 was investigated by N2 adsorption/desorption isotherms, as shown in Figure 4. As shown in Figure 4a, AC exhibits a I type isotherm, indicating its microporous structure. As for AC/MnO2, it displays a typical IV type isotherm,

indicating

the

presence

of

mesopores.

Furthermore,

the

Barrett-Joyner-Halenda (BJH) pore size distributions of AC and AC/MnO2 are shown in Figure 4b and d. Obviously, AC exhibits a pore size distribution below 2 nm, while with the MnO2 depositing on AC surfaces, the resultant AC/MnO2 displays a broad pore size distribution ranging from micropores to mesopores. The specific surface areas and pore volumes of AC and AC/MnO2 are listed in Table 1. It can be seen that AC exhibits a specific surface area of 2152.8 m2 g-1 and a pore volume of 1.30 cm3 g-1,

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much higher than those of AC/MnO2 (325.8 m2 g-1 and 0.72 cm3 g-1), which is consistent with previous report .43

Figure 4. N2 adsorption/desorption isotherms of (a) AC and (c) AC/MnO2 and corresponding BJH pore size distributions of (b) AC and (d) AC/MnO2 obtained by using adsorption branch.

Table 1 Specific surface areas and pore volumes of AC and AC/MnO2.

Sample

Specific surface area (m2

Pore volume (cm3 g-1)

g-1)

AC

2152.8

10


1.30

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AC/MnO2

325.8

0.72

3.2 Electrochemical characterization

Before

desalinization

tests,

we

first

investigated

the

electrochemical

performances of AC and AC/MnO2 film electrodes in 1 M NaCl solution by using CV measurements. As shown in Figure 5a, all CV curves display a relatively rectangular shape and no obvious redox peak can be observed. As calculated according to equation (1), the specific capacitances at a scan rate of 20 mV s-1 are 122.5 F g-1 for AC and 104.2 F g-1 for AC/MnO2, respectively. Additionally, the two materials display different potential stability windows (-0.8 - 0.2 V for AC and 0 - 1.0 V for AC/MnO2). As well known, limited by the decomposition potential of water (1.23 V), the potential window of symmetric capacitor in aqueous electrolyte is usually below 1.2 V. Once the potential window exceeds 1.2 V, the electrolyte will decompose. Fortunately, the asymmetric capacitor (ASC) is proposed as an effective method to improve the potential window. In this work, an ASC was constructed by using AC as negative electrode and AC/MnO2 as positive electrode in order to improve the potential window. The optimal mass ratio (m+/m- = 1.18) between positive and negative electrodes was estimated from the equation as follows:29

m + Cs − ×V = m − Cs + ×V

− +

(3)

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where m+ and m- are the mass of the film electrode materials (g), Cs+ and Cs- are the specific capacitances (F g-1), V+ and V- are the potential windows of the positive and negative electrodes (mV s-1), respectively. Figure 5b shows the CV curves of the ASC device measured at 20 mV s-1 in 1.0 M NaCl solution with different potential windows. These curves exhibit quasi-rectangular shapes without noticeable redox peaks even when the potential window is increased up to 1.8 V, implying an ideal capacitive behaviour in neutral aqueous medium for both electrodes. Considering the results of ASC, it should be believed that when mass ratio of positive electrode (AC/MnO2) to negative electrode (AC) is 1.18, a maximum operation voltage of 1.8 V can be achieved for AFCDI device.

Figure 5. (a) CV curves of AC and AC/MnO2 film electrodes at a scan rate of 20 mV s-1. (b) Optimization of the potential window of ASC measured by using CV tests at a scan rate of 20 mV s-1.

3.3 Desalinization performance test

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The desalinization performance of AFCDI device was investigated in 0.1 M NaCl solution at a constant operation voltage of 1.8 V for 2 h. For comparison, conventional FCDI device was investigated in 0.1 M NaCl solution at a constant operation voltage of 1.2 V for 2 h. It should be noted that due to the limitation of decomposition potential of water (1.23 V), the maximum operation voltage of FCDI device can be only up to 1.2 V. However, for AFCDI device, due to the expanded potential window between positively polarized AC/MnO2 electrode and negatively polarized AC electrode (as revealed in Figure 5b), its operation voltage can reach an improved value of 1.8 V without any unwanted electrochemical reactions (e.g. water decomposition). In practical cases, no obvious phenomenon of water decomposition has been observed. Figure 6a shows the variation of relative NaCl concentration (C/C0) for both FCDI and AFCDI devices within 2 h. It can be seen that AFCDI displays a higher salt removal efficiency of 78% than conventional FCDI (59%), and moreover, this value is also higher than those for other FCDI devices reported previously (Table 2). This can be ascribed to two reasons: (i) due the expanded potential window between negative AC electrode and positive AC/MnO2 electrode, AFCDI displays an improved operation voltage of 1.8 V compared with FCDI (1.2 V). (ii) AC/MnO2 exhibits a hydrophilic feature, while AC displays high hydrophobicity, as revealed by the contact angel tests shown in Figure S2 (Supporting Information). In addition, AFCDI device was also investigated in higher concentration NaCl solutions (e.g. 0.2 M, 0.3 M and 0.5 M), as shown in Figure S3 (Supporting Information). The results

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indicate that AFCDI still remains excellent desalination performances in highly concentrated solution.

Figure 6b shows the mean electrosorption rates of FCDI and AFCDI devices and corresponding error bars. It is worthy nothing that the data shown in Figure 6b are obtained by repeating the fabrication of AFCDI device for several times. The mean electrosorption rate of AFCDI is compared with the values in state-of-the-art CDI-based desalination field (Table 3). Clearly, AFCDI exhibits a much higher value than those achieved for CDI and membrane CDI (MCDI) devices reported by now. These results demonstrate the superiority of the novel AFCDI device in this work.

Figure 6. (a) Normalized concentration profiles, and (b) mean electrosorption rates for FCDI and AFCDI devices.

Table 2 Comparison of salt removal efficiency for AFCDI and FCDI devices. Device

Initial NaCl

Applied voltage

concentration (mg L-1) FCDI37

(V)

5.9

1.2

14


Salt removal efficiency (%) 39.9

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Single

1

1.2

70

5.8

1.2

72.2

5.8

1.8

78

module FCDI39

Neutralization FCDI45

AFCDI (this work)

Table 3 Comparison of mean electrosorption rates for AFCDI, FCDI, MCDI and CDI devices in NaCl solution.

Device

Surface Area

Electrode

(m2 g-1) 3D hierarchical carbons//3D

1036.8

Pore volume (cm3 g-1)

2.62

Mean

Initial NaCl concentration

Applied voltage

(mg L-1)

(V)

~30

2.0

0.027

1.2

0.039

1.6

0.071

2.0

0.098

electrosorption rate (mg g-1 min-1)

46

hierarchical carbons

3D graphene//3D graphene47

339

-

~50

CDI Ordered mesoporous carbons//ordered mesoporous carbons

844

0.90

~25

1.2

0.008

526.7

3.13

~500

1.2

0.53

48

3D nitrogen-doped graphene//3D nitrogen-doped

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graphene49 Graphene//graphene50

488

51.01

~25

2.0

0.033

Hierarchical carbon fibers//hierarchical

428

0.138

~90

1.6

0.013

410

-

~4000

1.2

0.20

187.6

-

~500

1.2

1.89

2535

1.50

~30

1.2

1.08

778.0

0.502

~580

1.2

0.16

134

0.664

30

1.8

0.27

-

-

25

1.2

0.080

-

-

~5844

1.2

1.97

391

0.49

750

2.0

1.32

-

-

15000

1.2

3.71

51

carbon fibers

Mesoporous carbons// mesoporous carbons52 3D graphene/TiO2// 3D graphene/TiO253 Mesoporous carbons// mesoporous carbons36 Nitrogen-doped carbons// nitrogen-doped carbons29 AC//Carbon nanotubes/MnO254 Carbon nanotubes/carbon nanofibers//carbon nanotubes/carbon nanofibers55 MCDI

Na4Mn9O18//AC56 Carbon nanotubes/graphene //carbon nanotubes/graphene57

FCDI

AC//AC58

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AC //AC/MnO2 (this work)

325.8

0.72

~5844

1.8

9.67

3.4 Kim-Yoon plot analysis Kim-Yoon plot is an effective tool to evaluate the deionization performance of CDI electrode materials, which was first proposed by Yoon et al.12 In this work, we utilize the Kim-Yoon plot to evaluate the deionization performance of our AFCDI device. The electrosorption capacity at t min (Γt, mg g-1) and corresponding mean electrosorption rate (v, mg g-1 min-1) were calculated according to the following equations, respectively:

Γt =

(C 0 − Ct )× V m

(4)

v = Γt t

(5)

where C0 and Ct are the initial concentration and the concentration at t min (mg L-1), respectively. V is the volume of the NaCl aqueous solution (L), m represents the mass of the active materials (g), and t is the time of electrosorption process (min). As shown in Figure 8, the Kim-Yoon plot for AFCDI device shifts towards the upper and right region (i.e. higher deionization capacity and faster deionization rate) compared to conventional FCDI device, demonstrating that the AFCDI device integrates the merits of both high deionization capacity and fast deionization rate. Therefore, it is believed that the AFCDI device should be a promising desalinization device for high-concentration saline water treatment.

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Figure 7. Kim-Yoon plots for FCDI and AFCDI devices.

4. Conclusion In this work, we propose a novel AFCDI device by using AC/MnO2 suspension as positive electrode and AC suspension as negative electrode. The desalinization performance of AFCDI device was investigated in 0.1 M NaCl solution, and it displays an high salt removal efficiency of 78%, much higher than that of conventional FCDI (59%), and the current values reported for other FCDI devices. Additionally, Kim-Yoon plot model analysis reveals that AFCDI device integrates the merits of both high deionization capacity and fast deionization rate, indicating the superiority of the AFCDI device. It is believed that the AFCDI device should be a promising desalinization device for high-concentration saline water treatment.

Author Information Corresponding Author

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* E-mail address: [email protected] Tel.:+86 21 62234132; fax: +86 21 62234321 Notes

The authors declare no competing financial interest. Acknowledgements Financial supports from National Natural Science Foundation of China (No. 21276087) and Outstanding Doctoral Dissertation Cultivation Plan (PY2015040) are gratefully acknowledged. References 1.

Humplik, T.; Lee, J.; O’hern, S.; Fellman, B.; Baig, M.; Hassan, S.; Atieh, M.;

Rahman, F.; Laoui, T.; Karnik, R., Nanostructured materials for water desalination. Nanotechnology 2011, 22 (29), 292001. 2.

Elimelech, M.; Phillip, W. A., The future of seawater desalination: energy,

technology, and the environment. Science 2011, 333 (6043), 712-717. 3.

Kim, S. J.; Ko, S. H.; Kang, K. H.; Han, J., Direct seawater desalination by ion

concentration polarization. Nat. Nanotechnol. 2010, 5 (4), 297-301. 4.

Suss, M.; Porada, S.; Sun, X.; Biesheuvel, P.; Yoon, J.; Presser, V., Water

desalination via capacitive deionization: what is it and what can we expect from it? Energy Environ. Sci. 2015, 8, 2296-2319.

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

5.

Gohari, A.; Eslamian, S.; Mirchi, A.; Abedi-Koupaei, J.; Bavani, A. M.; Madani,

K., Water transfer as a solution to water shortage: a fix that can backfire. J. Hydrol. 2013, 491, 23-39. 6.

Lee, W. J.; Maiti, U. N.; Lee, J. M.; Lim, J.; Han, T. H.; Kim, S. O.,

Nitrogen-doped carbon nanotubes and graphene composite structures for energy and catalytic applications. Chem. Commun. 2014, 50 (52), 6818-6830. 7.

Liu, Y.; Nie, C.; Liu, X.; Xu, X.; Sun, Z.; Pan, L., Review on carbon-based

composite materials for capacitive deionization. RSC Adv. 2015, 5 (20), 15205-15225. 8.

Anderson, M. A.; Cudero, A. L.; Palma, J., Capacitive deionization as an

electrochemical means of saving energy and delivering clean water. Comparison to present desalination practices: Will it compete? Electrochim. Acta 2010, 55 (12), 3845-3856. 9.

Porada, S.; Zhao, R.; Van Der Wal, A.; Presser, V.; Biesheuvel, P. M., Review on

the science and technology of water desalination by capacitive deionization. Prog. Mater. Sci. 2013, 58 (8), 1388-1442. 10. Porada, S.; Feng, G.; Suss, M.; Presser, V., Capacitive deionization in organic solutions: case study using propylene carbonate. RSC Adv. 2016, 6 (7), 5865-5870. 11. Yeh, C.-L.; Hsi, H.-C.; Li, K.-C.; Hou, C.-H., Improved performance in capacitive deionization of activated carbon electrodes with a tunable mesopore and micropore ratio. Desalination 2015, 367, 60-68.

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12. Kim, T.; Yoon, J., CDI ragone plot as a functional tool to evaluate desalination performance in capacitive deionization. RSC Adv. 2015, 5 (2), 1456-1461. 13. Dykstra, J.; Zhao, R.; Biesheuvel, P.; van der Wal, A., Resistance identification and rational process design in Capacitive Deionization. Water Res. 2016, 88, 358-370. 14. Hemmatifar, A.; Stadermann, M.; Santiago, J. G., Two-Dimensional Porous Electrode Model for Capacitive Deionization. J. Phys. Chem. C 2015, 119 (44), 24681-24694. 15. Tang, W.; Kovalsky, P.; He, D.; Waite, T. D., Fluoride and nitrate removal from brackish groundwaters by batch-mode capacitive deionization. Water Res. 2015, 84, 342-349. 16. He, D.; Wong, C. E.; Tang, W.; Kovalsky, P.; Waite, T. D., Faradaic Reactions in Water Desalination by Batch-Mode Capacitive Deionization. Environ. Sci. Technol. Lett. 2016, 3, 222-226. 17. Suss, M. E.; Biesheuvel, P.; Baumann, T. F.; Stadermann, M.; Santiago, J. G., In situ spatially and temporally resolved measurements of salt concentration between charging porous electrodes for desalination by capacitive deionization. Environ. Sci. Technol. 2014, 48 (3), 2008-2015. 18. Gao, X.; Landon, J.; Neathery, J. K.; Liu, K., Modification of carbon xerogel electrodes for more efficient asymmetric capacitive deionization. J. Electrochem. Soc. 2013, 160 (9), 106-112.

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

19. Qu, Y.; Baumann, T. F.; Santiago, J. G.; Stadermann, M., Characterization of resistances of a capacitive deionization system. Environ. Sci. Technol. 2015, 49 (16), 9699-9706. 20. Gao, X.; Omosebi, A.; Landon, J.; Liu, K., Surface charge enhanced carbon electrodes for stable and efficient capacitive deionization using inverted adsorption– desorption behavior. Energy Environ. Sci. 2015, 8 (3), 897-909. 21. Cohen, I.; Avraham, E.; Noked, M.; Soffer, A.; Aurbach, D., Enhanced charge efficiency in capacitive deionization achieved by surface-treated electrodes and by means of a third electrode. J. Phys. Chem. C 2011, 115 (40), 19856-19863. 22. Li, H.; Liang, S.; Gao, M.; Li, G.; Li, J.; He, L., The study of capacitive deionization behavior of a carbon nanotube electrode from the perspective of charge efficiency. Water Sci. Technol. 2015, 71 (1), 83-88. 23. Suss, M. E.; Baumann, T. F.; Bourcier, W. L.; Spadaccini, C. M.; Rose, K. A.; Santiago, J. G.; Stadermann, M., Capacitive desalination with flow-through electrodes. Energy Environ. Sci. 2012, 5 (11), 9511-9519. 24. Bian, Y.; Yang, X.; Liang, P.; Jiang, Y.; Zhang, C.; Huang, X., Enhanced desalination performance of membrane capacitive deionization cells by packing the flow chamber with granular activated carbon. Water Res. 2015, 85, 371-376. 25. Liang, P.; Yuan, L.; Yang, X.; Zhou, S.; Huang, X., Coupling ion-exchangers with inexpensive activated carbon fiber electrodes to enhance the performance of

22


Page 22 of 29

Page 23 of 29

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


capacitive deionization cells for domestic wastewater desalination. Water Res. 2013, 47 (7), 2523-2530. 26. Lee, J.; Kim, S.; Kim, C.; Yoon, J., Hybrid capacitive deionization to enhance the desalination performance of capacitive techniques. Energy Environ. Sci. 2014, 7 (11), 3683-3689. 27. Li, H. B.; Gao, Y.; Pan, L. K.; Zhang, Y. P.; Chen, Y. W.; Sun, Z., Electrosorptive desalination by carbon nanotubes and nanofibres electrodes and ion-exchange membranes. Water Res. 2008, 42 (20), 4923-4928. 28. Xu, X.; Pan, L.; Liu, Y.; Lu, T.; Sun, Z., Enhanced capacitive deionization performance of graphene by nitrogen doping. J. Colloid Interf. Sci. 2015, 445, 143-150. 29. Liu, N.-L.; Dutta, S.; Salunkhe, R. R.; Ahamad, T.; Alshehri, S. M.; Yamauchi, Y.; Hou, C.-H.; Wu, K. C.-W., ZIF-8 derived, nitrogen-doped porous electrodes of carbon polyhedron particles for high-performance electrosorption of salt ions. Sci. Rep. 2016, 6, 28847. 30. Qian, B.; Wang, G.; Ling, Z.; Dong, Q.; Wu, T.; Zhang, X.; Qiu, J., Sulfonated Graphene as Cation‐Selective Coating: A New Strategy for High‐Performance Membrane Capacitive Deionization. Adv. Mater. Interfaces 2015, 2 (16), 1500372. 31. Xu, X.; Pan, L.; Liu, Y.; Lu, T.; Sun, Z.; Chua, D. H., Facile synthesis of novel graphene sponge for high performance capacitive deionization. Sci. Rep. 2015, 5, 8458.

23



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

32. Pan, H.; Yang, J.; Wang, S.; Xiong, Z.; Cai, W.; Liu, J., Facile fabrication of porous carbon nanofibers by electrospun PAN/dimethylsulfone for capacitive deionization. J. Mater. Chem. A 2015, 3, 13827-13834. 33. El-Deen, A. G.; Barakat, N. A.; Khalil, K. A.; Kim, H. Y., Hollow carbon nanofibers as an effective electrode for brackish water desalination using the capacitive deionization process. New J. Chem. 2014, 38 (1), 198-205. 34. Wen, X.; Zhang, D.; Yan, T.; Zhang, J.; Shi, L., Three-dimensional graphene-based hierarchically porous carbon composites prepared by a dual-template strategy for capacitive deionization. J. Mater. Chem. A 2013, 1 (39), 12334-12344. 35. Wang, G.; Dong, Q.; Wu, T.; Zhan, F.; Zhou, M.; Qiu, J., Ultrasound-assisted preparation of electrospun carbon fiber/graphene electrodes for capacitive deionization: Importance and unique role of electrical conductivity. Carbon 2016, 103, 311-317. 36. Dutta, S.; Huang, S.-Y.; Chen, C.; Chen, J. E.; Alothman, Z. A.; Yamauchi, Y.; Hou, C.-H.; Wu, K. C.-W., Cellulose Framework Directed Construction of Hierarchically Porous Carbons Offering High-Performance Capacitive Deionization of Brackish Water. ACS Sustain. Chem. Eng. 2016, 4 (4), 1885-1893. 37. Jeon, S.-i.; Park, H.-r.; Yeo, J.-g.; Yang, S.; Cho, C. H.; Han, M. H.; Kim, D. K., Desalination via a new membrane capacitive deionization process utilizing flow-electrodes. Energ. Environ. Sci. 2013, 6 (5), 1471-1475.

24


Page 24 of 29

Page 25 of 29

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


38. Porada, S.; Weingarth, D.; Hamelers, H. V.; Bryjak, M.; Presser, V.; Biesheuvel, P., Carbon flow electrodes for continuous operation of capacitive deionization and capacitive mixing energy generation. J. Mater. Chem. A 2014, 2 (24), 9313-9321. 39. Rommerskirchen, A.; Gendel, Y.; Wessling, M., Single module flow-electrode capacitive deionization for continuous water desalination. Electrochem. Commun. 2015, 60, 34-37. 40. Hatzell, K. B.; Hatzell, M. C.; Cook, K. M.; Boota, M.; Housel, G. M.; McBride, A.; Kumbur, E. C.; Gogotsi, Y., Effect of oxidation of carbon material on suspension electrodes for flow electrode capacitive deionization. Environ. Sci. Technol. 2015, 49 (5), 3040-3047. 41. Hatzell, K. B.; Iwama, E.; Ferris, A.; Daffos, B.; Urita, K.; Tzedakis, T.; Chauvet, F.; Taberna, P.-L.; Gogotsi, Y.; Simon, P., Capacitive deionization concept based on suspension electrodes without ion exchange membranes. Electrochem. Commun. 2014, 43, 18-21. 42. Jeon, S.-I.; Yeo, J.-G.; Yang, S.; Choi, J.; Kim, D. K., Ion storage and energy recovery of a flow-electrode capacitive deionization process. J. Mater. Chem. A 2014, 2 (18), 6378-6383. 43. Hatzell, K. B.; Fan, L.; Beidaghi, M.; Boota, M.; Pomerantseva, E.; Kumbur, E. C.; Gogotsi, Y., Composite manganese oxide percolating networks as a suspension electrode for an asymmetric flow capacitor. ACS Appl. Mater. Inter. 2014, 6 (11), 8886-8893.

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

44. Khomenko, V.; Raymundo-Pinero, E.; Béguin, F., Optimisation of an asymmetric manganese oxide/activated carbon capacitor working at 2V in aqueous medium. J. Power Sources 2006, 153 (1), 183-190. 45. Wang, M.; Hou, S.; Liu, Y.; Xu, X.; Lu, T.; Zhao, R.; Pan, L., Capacitive neutralization deionization with flow electrodes. Electrochim. Acta 2016, 216, 211-218. 46. Wen, X.; Zhang, D.; Shi, L.; Yan, T.; Wang, H.; Zhang, J., Three-dimensional hierarchical porous carbon with a bimodal pore arrangement for capacitive deionization. J. Mater. Chem. 2012, 22 (45), 23835-23844. 47. Wang, H.; Zhang, D.; Yan, T.; Wen, X.; Zhang, J.; Shi, L.; Zhong, Q., Three-dimensional macroporous graphene architectures as high performance electrodes for capacitive deionization. J. Mater. Chem. A 2013, 1 (38), 11778-11789. 48. Zou, L.; Li, L.; Song, H.; Morris, G., Using mesoporous carbon electrodes for brackish water desalination. Water Res. 2008, 42 (8), 2340-2348. 49. Xu, X.; Sun, Z.; Chua, D. H.; Pan, L., Novel nitrogen doped graphene sponge with ultrahigh capacitive deionization performance. Sci. Rep. 2015, 5, 11225. 50. Li, H.; Zou, L.; Pan, L.; Sun, Z., Novel graphene-like electrodes for capacitive deionization. Environ. Sci. Technol. 2010, 44 (22), 8692-8697. 51. Wang, G.; Dong, Q.; Ling, Z.; Pan, C.; Yu, C.; Qiu, J., Hierarchical activated carbon nanofiber webs with tuned structure fabricated by electrospinning for capacitive deionization. J. Mater. Chem. 2012, 22 (41), 21819-21823.

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Page 26 of 29

Page 27 of 29

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


52. Mayes, R. T.; Tsouris, C.; Kiggans Jr, J. O.; Mahurin, S. M.; DePaoli, D. W.; Dai, S., Hierarchical ordered mesoporous carbon from phloroglucinol-glyoxal and its application in capacitive deionization of brackish water. J. Mater. Chem. 2010, 20 (39), 8674-8678. 53. Yin, H.; Zhao, S.; Wan, J.; Tang, H.; Chang, L.; He, L.; Zhao, H.; Gao, Y.; Tang, Z., Three‐dimensional graphene/metal oxide nanoparticle hybrids for high‐ performance capacitive deionization of saline water. Adv. Mater. 2013, 25 (43), 6270-6276. 54. Chen, B.; Wang, Y.; Chang, Z.; Wang, X.; Li, M.; Liu, X.; Zhang, L.; Wu, Y., Enhanced capacitive desalination of MnO 2 by forming composite with multi-walled carbon nanotubes. RSC Adv. 2016, 6 (8), 6730-6736. 55. Li, H.; Gao, Y.; Pan, L.; Zhang, Y.; Chen, Y.; Sun, Z., Electrosorptive desalination by carbon nanotubes and nanofibres electrodes and ion-exchange membranes. Water Res. 2008, 42 (20), 4923-4928. 56. Lee, J.; Kim, S.; Kim, C.; Yoon, J., Hybrid capacitive deionization to enhance the desalination performance of capacitive techniques. Energ. Environ. Sci. 2014, 7 (11), 3683-3689. 57. Wimalasiri, Y.; Zou, L., Carbon nanotube/graphene composite for enhanced capacitive deionization performance. Carbon 2013, 59, 464-471.

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58. Gendel, Y.; Rommerskirchen, A. K. E.; David, O.; Wessling, M., Batch mode and continuous desalination of water using flowing carbon deionization (FCDI) technology. Electrochem. Commun. 2014, 46, 152-156.

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Entry for the Table of Contents

Ultrahigh desalinization performance of asymmetric flow-electrode capacitive deionization device with an improved operation voltage of 1.8 V Xingtao Xu, Miao Wang, Yong Liu, Ting Lu and Likun Pan∗

A novel asymmetric flow-electrode capacitive deionization device is proposed with a high salt removal efficiency in 0.1 M NaCl solution.

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Ultrahigh Desalinization Performance of Asymmetric Flow-Electrode

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