Bromide Ions Specific Removal and Recovery by Electrochemical

Subscriber access provided by Universitaetsbibliothek | Johann Christian Senckenberg

Environmental Processes

Bromide ions specific removal and recovery by electrochemical desalination Izaak Cohen, Barak Shapira, Eran Avraham, Abraham Soffer, and Doron Anurbach Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.8b00282 • Publication Date (Web): 11 May 2018 Downloaded from http://pubs.acs.org on May 12, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 25

Environmental Science & Technology

1

Bromide

ions

specific

removal

and

recovery

2

electrochemical desalination

3

Izaak Cohen*, Barak Shapira, Eran Avraham, Abraham Soffer, Doron Aurbach

4

Department of Chemistry, Bar-Ilan University, Ramat-Gan 5290002, Israel

5

* Corresponding author: [email protected]

by

6 7

Abstract

8

Removal and recovery of bromide ions by electro-oxidation and electro-reduction are

9

presented using hybrid physical adsorption and capacitive deionization cells, which

10

contain activated carbon cloth electrodes. This is a proof of concept research with results,

11

which indicate that when comparing the removal and recovery quantities of bromide and

12

chloride ions (starting with the same initial concentration of 0.05M for both salts), the

13

desalination capacity of the bromide ions is larger by almost two orders of magnitude

14

than that of the chloride ions; thus, we obtained specific desalination of bromide ions

15

from a solution containing chloride ions. Removal and recovery of 3.5 mmoles of

16

bromide ions were achieved by a working electrode with 1 gr of activated carbon cloth,

17

and the calculated energy consumption for the removal and recovery of 1 gr of bromide

18

ions was about 2.24 kJ/gr.

19

Page 1 of 25 ACS Paragon Plus Environment


20

1. Introduction

21

The bromine industry encompasses a variety of applications, including fire

22

extinguishers, agriculture, and healthcare. The industrial waste of power generation,

23

bromine factories and hydraulic fracturing1 contains a vast amount of bromide ions that

24

can be recovered and reused.

25

Removal and recovery of bromide ions was done in the past for environmental and

26

economic purposes1–4. There are problematic environmental aspects and concerns when

27

potable water contains traces of bromide ions, because their presence can lead to the

28

formation of trihalomethanes (THMs) 3,5 and haloacetic acids6 as by products due to

29

chlorination, and bromate anions due to ozonation7,8. Such species are forbidden to

30

excide levels around 4X10-7, 3X10-7 and 7.8X10-8 M respectively by the United States

31

Environmental Protection Agency due to detrimental effects of THMs on the liver,

32

kidney or the central nervous system. Also, there is a serious risk that the above three

33

types of hazardous materials are carcinogenic. Therefore, researchers are trying to avoid

34

contamination of water reservoirs by bromine compounds3,4 by removal of bromide ions

35

from contaminated water sources1,2.

36

Regular desalination methods, such as reverse osmosis and direct distillation,

37

require large amounts of energy to produce high pressures and temperatures, respectively,

38

while desalinating with no selectivity towards the removal of bromide9–11. Hence,

39

previous research used methods such as electro-oxidation of bromide ions1–3 and ion-

40

exchange resin4 for specific removal of bromide ions from concentrated solutions and tap

41

water. These developed working methods were not suitable for industrial processes due

42

to the cost efficiency of the processes and the products. The electro-oxidation of bromide


Page 2 of 25

Page 3 of 25


43

ions requires the addition of KI solution (that has a price) to change the bromine back to

44

bromide. Producing I2 in turn, needs investment of further efforts.

45

membrane and stable electrodes costs, and also a problem related to the poor regeneration

46

of the exchange resin. The new concept that we develop and describe herein is based on

47

the use of a special cell which includes simple activated carbon electrodes. By single

48

charge/discharge cycles this cell removes and recovers selectively bromide ions, from a

49

mixed solution of bromide and chloride ions. This concept may lead to the development

50

of a new technology that might be implemented practically in industrial processes.

51

Hence, this paper shows a working proof of concept. However, further experimental

52

work is required before the concept we show herein can be translated to fully practical

53

separation processes.

There are the

54

For selective electro-oxidation of bromide ions (Eq. 1), we need to consider the

55

electro-oxidation potentials of chloride ions and water (Eqs. 2 and 3), which are quite

56

close (the equations were taken from handbook of chemistry and physics12).

57

2 ← → + 2 = 1.087 ,

(1)

58

2 ← → + 2 = 1.358 ,

(2)

59

! 2 ← → + 4 + 4 = 1.229 .

(3)

60

Based on a previous study with graphite electrodes1, specific electro-oxidation of

61

bromide to bromine was achieved using a solution containing different concentrations of

62

chloride and bromide ions, without generating chlorine or oxygen. However, in that study

63

a potassium iodide solution was used to capture the released bromine gas, and the use of

64

graphite required a membrane to separate the anode and cathode, and the cathode

65

(negative electrode) produced hydrogen.



66

In this study, we use hybrid physical adsorption and capacitive deionization

67

(HPA-CDI) technology, which is based on capacitive deionization (CDI), an energy-

68

efficient water desalination technology13–15. CDI cells contain high-surface-area

69

electrodes, which are usually activated carbon materials that when polarized below the

70

water-splitting potential (Eq. 3) create an electrical double layer that adsorbs the counter-

71

ions to the high surface area of the electrodes, thereby producing a diluted solution. When

72

discharged, the solution becomes concentrated, and is therefore routed to a waste stream.

73

Removal and recovery of bromide ions by electro-oxidation and electro-reduction

74

were achieved using asymmetric CDI (A-CDI) cells, which contain activated carbon

75

cloth (ACC) as electrodes. A-CDI cells were used previously to achieve better water

76

desalination performance16–18. Here, we used A-CDI cells to enable electro-oxidation of

77

bromide ions (applying a positive potential of around 1 V on the positive polarized

78

electrodes, see Eq. 1), while mitigating the water electrolysis. A-CDI cells enable

79

asymmetric polarization of the electrodes, whereby the applied potential is divided

80

between the positive and negative electrodes asymmetrically, a higher potential falling on

81

the positive electrode (with low surface area).

82

The essentially non-polarized activated carbon exhibits a strong interaction with

83

bromine molecules, and is thus commonly used in industry. A study that was conducted

84

using carbon black with surface area of only 100 m2/gr showed a physical adsorption of

85

bromine with a specific capacity capability of around 1.25 mmole/gr19. Upon electro-

86

oxidation of the bromide ions, the bromine molecules are formed near the surface of the

87

positive ACC electrodes. Thus, the bromine molecules are encouraged to physically

88

adsorb to the surface of the ACC electrodes; hence, we call this technology hybrid


Page 4 of 25

Page 5 of 25


89

physical adsorption and capacitive deionization (HPA-CDI). When discharging the

90

electrodes, bromine molecules that are physically connected to the positive ACC

91

electrodes are reduced back to bromide ions and go back to the solution.

92



93

2. Materials and Methods

94

2.1. CDI cell structures

95

The flow-through HPA-CDI cell structure has a flange-type design (Figure 1).

96

The solution is introduced through plates to ensure homogeneous flow through the entire

97

circular cross-section of the cell. The electrodes were made of commercial activated

98

carbon cloth (ACC-5092-15, Nippon Kynol, Japan) with high surface area (1440 m2/gr

99

BET) originating from phenol-formaldehyde polymeric fibers that underwent

100

carbonization and activation. The HPA-CDI cells contained 24 ACC disc electrodes – 4

101

positively polarized working electrodes (WEs) and 20 negatively polarized counter

102

electrodes (CEs). Sheets of porous polyethylene cloth served as separators between the

103

electrodes and exhibited low resistance to the solution flow. Silicon glue was soaked into

104

the rims of the separator discs at the perimeters, thereby forming soft and elastic gaskets.

105

These separator sheets with gaskets at their perimeters provided the necessary mechanical

106

and electrical separation between the electrodes (thereby preventing short circuits). Ring

107

spacers made of poly-tetra-fluoro-ethylene (PTFE) were used for the electrode casings,

108

with 0.5 and 2.5 mm deep grooves that held the positive (one ACC disc) and negative

109

(five ACC discs) carbon electrodes, respectively. The current collectors were made of

110

graphite paper sheets (Grafoil) that were attached to the electrodes in the cell; they were

111

perforated to allow a smooth flow of solution. A reference electrode (RE) was placed at

112

the middle of the cell: a silver mesh covered by AgCl (by anodization of the mesh in 0.1

113

M HCl solution). When all HPA-CDI cell components – the electrodes in their plastic

114

cases, the graphite sheet current collectors, and the separator sheets with polymeric

115

gaskets at their perimeters – were pressed together, in the right order, they formed a


Page 6 of 25

Page 7 of 25


116

hermetically sealed flow-through multi-electrode electrochemical cell that functioned as a

117

three-electrode cell.

118

2.2. System set-up

119

A graphical description of the layout of the entire setup that was used here is

120

presented in Figure 2. A 5-liter round-bottom flask was used as the solution reservoir for

121

the experimental system. It contained 5 liters of 0.05 M NaCl (>99.5% pure, Sigma-

122

Aldrich, USA) and 0.05 M NaBr (>99% pure, Strem Chemicals, USA), in highly purified

123

water (18.2 MΩ). Before the polarization of the HPA-CDI cell, the solution was

124

circulated for air evacuation in a closed system, which included the electrochemical cell,

125

the pumps, and the conductivity probe. The conductometer probe (Metrohm, 712 model)

126

was connected to the outlet of the HPA-CDI cell to measure on-line the conductivity of

127

the solution, which flows out of the cell. In order to control the solution flow, a

128

parametric pump (Fluid Metering Inc.) was used, and the solution flow was calibrated to

129

8.5 ml/min. The potentials were applied to the cell by a Potentiostat (Metrohm, Autolab,

130

PGSTAT302N). When polarizing the cell electrodes, the system setup, as described in

131

Figure 2, was modified to an open system, where the solution exits the system for

132

analytical sampling.

133

2.3. Analytical tools

134

The collected samples were measured for a quantitative evaluation of bromide, bromate

135

and chloride ions solvated inside each sample solution. Ion chromatography was carried

136

out with 9X10-3 M of Na2CO3 (Dionex ICS-2100, Thermo Scientific) to measure the

137

weight of the different ions inside each sample. Additionally, the weights of the ions were

138

measured by titration with AgNO3 at a concentration of 0.01 M (848 Titrino Plus, Page 7 of 25 ACS Paragon Plus Environment


139

Metrohm) to confirm and evaluate the different ions, which were difficult to evaluate by

140

ion chromatography.

141


Page 8 of 25

Page 9 of 25

142


3. Results and discussion

143

CDI technology is usually employed for its capacitive electrostatic properties. To use

144

it for electrochemical reactions with bromide ions and to avoid electrochemical reactions

145

with chloride ions while using ACC electrodes, a preliminary study of the working

146

potential domains was conducted.

147

3.1. Comparison between chloride/chlorine and bromide/bromine redox reactions

148

by cyclic voltammetry

149

Two different solutions for cyclic voltammetry CV measurements were prepared:

150

one contained 0.05 M of NaCl, and the second contained 0.05 M of NaBr. The electrodes

151

used for the three-electrode cell were a saturated calomel electrode (SCE) as RE, and WE

152

and CE, which were both made from ACC (ACC-5092-15, Nippon Kynol, Japan), in a

153

weight ratio of 1 to 10, respectively. Figure 3 shows the CV results, where the x axis is

154

the potential that was measured between the RE and WE, and the y axis is the capacitance

155

(in units of F/gr). The scan rate was 1 mV/sec, the lower vortex potential was -0.1 V and

156

was the same for all CVs, and the upper vortex potentials were applied in an arithmetic

157

progression from 0.5 to 1 V, with a common increment of 0.05 V. Each CV was repeated

158

twice for every upper and lower vortex potential. It can be clearly seen from the results

159

that the chloride ions preserved almost the same electrostatic capacitive behavior, even

160

when the potential applied to the upper vortex was 1 V. In contrast, a redox reaction is

161

seen clearly in the CV plot, where the bromide ions were oxidized to bromine and

162

reduced back to bromide ions, starting from a potential of 0.8 V, and reached a stronger

163

bromide/bromine redox interaction when the applied upper vortex potential was higher.



164

The high peak of the anodic oxidation indicates that there are also irreversible

165

reactions like water splitting, which is also indicated by the NaCl high potential CVs.

166

Nevertheless, the results are consistent for each voltage scan range in Figure 3 that shows

167

reversible redox reactions, which confirms the reversibility of the bromide ions to

168

bromine conversion and vice versa.

169

3.2. Determination of the working potential domain of bromine/bromide by CV

170

To determine the working potential domain, we used a mixed solution of NaCl and

171

NaBr in concentrations of 0.05 and 0.005 M, respectively, where the sodium chloride salt

172

was used as a supporting electrolyte. This was based on the knowledge acquired from the

173

previous results (Figure 3) that show CVs of chloride ions in capacitive behavior when

174

using potentials lower or equal to 1 V. The three-electrode cell was the same as the

175

previous one (Section 3.1), using pristine electrodes. Figure 4 shows the CV plots

176

resulting from two different scan rates, 1 and 0.5 mV/sec. To focus on the redox

177

reactions, for which the beginning and termination are not clear in Figure 3, an electrolyte

178

with less bromide was required; to avoid the IR drop, we used a supporting electrolyte of

179

NaCl. A scan rate of 1 mV/sec for the low concentration of NaBr was too fast for the

180

diffusion kinetics of the dilute bromide ions; therefore, the plot indicated a capacitive

181

behavior. When using a slower scan rate of 0.5 mV/sec, the plot showed capacitive

182

behavior between the potentials of -0.1 and 0.5 V and electrochemical redox behavior

183

between 0.5 and 1 V.

184

3.3. Specific removal of bromide by flow-through HPA-CDI cell

185

After verifying the working potential domain (Section 3.2), specific desalination of

186

bromide by three electrodes was carried out. In this experiment we used a three electrode Page 10 of 25 ACS Paragon Plus Environment

Page 10 of 25

Page 11 of 25


187

HPA-CDI cell that enables to control the potential of the positive electrodes that were

188

polarized between 0.5 to 1 V. The cell type was a flow-through HPA-CDI cell with

189

pristine ACC electrodes in a weight ratio of 1 to 5 between the WE and CE respectively,

190

and the solution contained bromide and chloride ions at concentrations of 0.05 M each.

191

The HPA-CDI WEs were charged to 1 V and discharged to 0.5 V each cycle (when

192

polarized to 1 V the overall potential was measured to be around 1.4). An illustration of

193

the HPA-CDI cell is shown by figure S2 A-D in order to clearly explain its operation

194

mechanism. Figure 5 shows three cycles of specific removal and recovery of bromide

195

ions. The samples were taken after two preliminary cycles that were carried out to

196

achieve proper operation of the electrodes inside the HPA-CDI cell. The three cycles

197

repeated themselves with a moderate rise in the removal and recovery capacity of the

198

bromide ions, which can be explained by traces of air that were trapped inside the ACC

199

micro-pores after the preliminary cycles20. While the removal and recovery of the

200

bromide ions were dominant, those of the chloride ions were so low that the change in

201

concentration was within the error of the analytical method; hence, we achieved a

202

specific removal of bromide ions. Figure S1 shows a plot of conductivity vs. time that

203

was obtained by a conductivity probe that was located next to the exit of the CDI cell.

204

There is a significant correlation between the plot in figure 5, based on ex-situ ions

205

concentration measurements and the plot in figure S1 which show results of in-situ

206

conductivity measurements. Furthermore, all measured samples showed that the

207

concentration of bromate ions was less than 7.8X10-5 M, these measurements help to

208

exclude the presence of bromine inside the water, which is hazardous to the environment.



209

Figure 6 shows the current vs. time plot corresponding to Figure 5. The three cycles

210

shown in Fig. 6 are consistent, which provides another indication for the reproducibility

211

of the results, from the aspect of the electric charge. Based on the integral of the current,

212

the overall charges that were used for the charge and discharge in each cycle were

213

calculated.

214

The results from Figure 5 were calculated and organized into a column chart as

215

displayed in Figure 7, which compares the three cycles by the accumulated amount of

216

anions (bromide and chloride ions) that were adsorbed / desorbed by the HPA-CDI cell.

217

The y axis represents the amount of bromide and chloride ions that were removed and

218

recovered, in mmol units and normalized by the WE ACC electrode total weight, which

219

was 1.7 gr. The chart shows that the accumulated removal and recovery of bromide ions

220

in each cycle were almost the same; hence, almost all of the bromide ions that were

221

adsorbed and electro-oxidized into bromine inside the porous structure of the ACC

222

electrodes while polarizing to a potential of 1 V, were electrochemically reduced back

223

into the solution, as bromide ions, when the ACC electrodes were polarized back to a

224

lower potential of 0.5 V. Based on the results obtained when comparing the bromide and

225

chloride ion incremental removal and recovery, the bromide ion removal and recovery

226

were almost two orders of magnitude greater, thus we obtained specific desalination of

227

bromide ions from a solution that also contained chloride ions.

228

When working in capacitive mode, the capacitance of a 1 gr ACC electrode was

229

calculated to be about 100 F/gr (only per WE weight), which when translated to the

230

maximum salt removal (dividing by the Faraday constant) amounts to about 1 mmol. In

231

this study, we multiplied the maximal theoretical desalination capacity based on electric Page 12 of 25 ACS Paragon Plus Environment

Page 12 of 25

Page 13 of 25


232

double layer capacity by a factor of 3.5, to arrive at measurable bromide removal capacity

233

which is probably not the maximal removal capacity that can be reached. To better

234

understand how it is possible to obtain 3.5 mmol removal / recovery of bromide ions by 1

235

gr of ACC WE, we conceived a rational explanation. When the ACC electrodes are

236

polarized to 1 V, the bromide ions are electro-oxidized to bromine. Activated carbons

237

have a high physical connection with bromine molecules, and the bromine molecules are

238

created inside the micro-porous structure of the ACC, which impairs the molecule

239

movement back into the solution; meanwhile, other bromide ions, which are

240

electrostatically adsorbed into the pores and are electro-oxidized, interact with the

241

bromine molecules to give tribromide and pentabromide ions, as described by Eqs. 4–6: %&

242

+ '#($ ) ,

243

+ 2 '#($ + ,

244

) + '#($ + .

(4)

%*

(5)

%,

(6)

245

Bromide, tribromide and pentabromide equilibrium was well investigated21–23. Based on

246

this explanation, we can also understand the slow reduction of bromine to bromide ions

247

in Figure 4, which occurs due to the slow kinetics of the intermediate molecular

248

structures that finally leads to bromide ions.

249

To calculate the energy (J/gr) that was used for the removal and recovery of bromide

250

ions from a solution of NaCl and NaBr, both at a concentration of 0.05 M, we used Eq. 7:

251

012

= - ∙ / 3∙45

(7)

252

Where E is the energy used for the removal and recovery of 1 gr of bromide ions, V is the

253

overall potential used for the electro-oxidation of bromide ions to bromine, which was Page 13 of 25 ACS Paragon Plus Environment


Page 14 of 25

254

measured to be about 1.4 Volt, / 678 is the charge used for the removal of bromide ions,

255

n is the amount of bromide ions that were removed in moles, and Mw is the molar mass of

256

the bromide ions. The energy consumption for the removal and recovery of 1 gr of

257

bromide ions was calculated to be about 2.24 kJ/gr.

258

Nevertheless, when using ACC electrodes, there are problems arising from the oxidation

259

reactions of ACC electrodes that take place when the positive electrodes are polarized to

260

the potentials at which bromide ions are oxidized to bromine (eq. 8-9)24–26.

261

C + O → CO + 2 ! + 2 = 0.518 V SHE,

262

CO + O → CO + 2 ! + 2 = 0.104 V SHE.

(8) (9)

263

The surface oxidation reactions cannot be seen in the CV plots of Figures 3 and 4 that

264

show mostly a capacitive behavior related to the bromide redox reactions and thus are

265

undetectable electrochemically. The study was focused upon a new concept of operation.

266

For measuring the effect of surface oxidation reactions on the desalination process, long

267

term experiments are required. We intend to continue studying the long term degradation

268

processes in CDI operation (as we also explored in the past27).Additionally, because of

269

the electro oxidation of bromide ions to bromine molecules inside of the nanoporous

270

structure of the ACC we need to consider the possible production of hypobromouse acid,

271

that might enhance the surface oxidation of the positively polarized electrodes.

272

The experiments in this paper give a starting point for research into optimization of the

273

HPA-CDI method by using different concentrations of electrolytes and a variety of

274

activated carbon electrodes with various flow regimes and flow rates.

275


Page 15 of 25


276

References

277

(1)

Brines from Hydraulic Fracturing. Water Res. 2013, 47 (11), 3723–3731.

278 279

(2)

(3)

Kimbrough, D. E.; Suffet, I. H. Electrochemical Removal of Bromide and Reduction of THM Formation Potential in Drinking Water. Water Res. 2002, 36 (19), 4902–4906.

282 283

Hayri Yalçin, Timur Koç, V. P. HYDROGEN AND BROMINE PRODUCTION FROM CONCENTRATED SEA-WATER. Int. J. Hydrogen Energy 1997, 22 (10–11), 967–970.

280 281

Sun, M.; Lowry, G. V.; Gregory, K. B. Selective Oxidation of Bromide in Wastewater

(4)

Lv, L.; Wang, Y.; Wei, M.; Cheng, J. Bromide Ion Removal from Contaminated Water by

284

Calcined and Uncalcined MgAl-CO3 Layered Double Hydroxides. J. Hazard. Mater.

285

2008, 152 (3), 1130–1137.

286

(5)

Magazinovic, R. S.; Nicholson, B. C.; Mulcahy, D. E.; Davey, D. E. Bromide Levels in

287

Natural Waters: Its Relationship to Levels of Both Chloride and Total Dissolved Solids

288

and the Implications for Water Treatment. Chemosphere 2004, 57 (4), 329–335.

289

(6)

Heller-Grossman, L.; Manka, J.; Limoni-Relis, B.; Rebhun, M. Formation and

290

Distribution of Haloacetic Acids, THM and TOX in Chlorination of Bromide-Rich Lake

291

Water. Water Res. 1993, 27 (8), 1323–1331.

292

(7)

J. AWWA 1995, 87, 58–70.

293 294

(8)

Krasner, S. T.; Glaze, W. H.; Weinberg, H. S. Formation and Control of Bromate During Ozonation of Waters Containing Bromide. J. AWWA 1993, 85 (1), 73.

295 296

Siddiqui Mohamed S., Amy Gary L., R. R. G. Bromate Ion Formation: A Critical Review.

(9)

Epsztein, R.; Shaulsky, E.; Dizge, N.; Roy, Y.; Warsinger, D. M.; Elimelech, M. Ionic

297

Charge Density-Dependent Donnan Exclusion in Nanofiltration of Monovalent Anions.

298

Environ. Sci. Technol. 2018, before submission.



299

(10)

and How to Avoid Them: A Review. Sep. Purif. Technol. 2008, 63 (2), 251–263.

300 301

Van der Bruggen, B.; Manttari, M.; Nystrom, M. Drawbacks of Applying Nanofiltration

(11)

Mohammad, A. W.; Teow, Y. H.; Ang, W. L.; Chung, Y. T.; Oatley-Radcliffe, D. L.;

302

Hilal, N. Nanofiltration Membranes Review: Recent Advances and Future Prospects.

303

Desalination 2015, 356, 226–254.

304

(12)

Chief, Ed.; CRC.

305 306

(13)

AlMarzooqi, F. a.; Al Ghaferi, A. a.; Saadat, I.; Hilal, N. Application of Capacitive Deionisation in Water Desalination: A Review. Desalination 2014, 342, 3–15.

307 308

HANDBOOK OF CHEMISTRY and PHYSICS, 98th Editi.; John R. Rumble Editor-in-

(14)

Porada, S.; Zhao, R.; van der Wal, a.; Presser, V.; Biesheuvel, P. M. Review on the

309

Science and Technology of Water Desalination by Capacitive Deionization. Prog. Mater.

310

Sci. 2013, 58 (8), 1388–1442.

311

(15)

Present and Future (a Review). Desalination 2008, 228 (1–3), 10–29.

312 313

Oren, Y. Capacitive Deionization (CDI) for Desalination and Water Treatment — Past,

(16)

Gao, X.; Landon, J.; Neathery, J. K.; Liu, K. Modification of Carbon Xerogel Electrodes

314

for More Efficient Asymmetric Capacitive Deionization. J. Electrochem. Soc. 2013, 160

315

(9), E106–E112.

316

(17)

Omosebi, A.; Gao, X.; Landon, J.; Liu, K. Asymmetric Electrode Configuration for

317

Enhanced Membrane Capacitive Deionization. ACS Appl. Mater. Interfaces 2014, 6 (15),

318

12640–12649.

319

(18)

Lado, J. J.; Pérez-Roa, R. E.; Wouters, J. J.; Isabel Tejedor-Tejedor, M.; Anderson, M. a.

320

Evaluation of Operational Parameters for a Capacitive Deionization Reactor Employing

321

Asymmetric Electrodes. Sep. Purif. Technol. 2014, 133, 236–245.


Page 16 of 25

Page 17 of 25

322


(19)

Chem. 1955, 47 (5), 1053–1062.

323 324

(20)

Walker, G. M.; Weatherley, L. R. Adsorption of Acid Dyes on to Granular Activated Carbon in Fixed Beds. Water Res. 1997, 31 (8), 2093–2101.

325 326

Watson, J.; Parkinson, D. Adsorption of Iodine and Bromine By Carbon Black. Ind. Eng.

(21)

Bianchini, R.; Chiappe, C. Stereoselectivity and Reversibility of Electrophilic Bromine

327

Addition to Stilbenes in Chloroform: Influence of the Bromide-Tribromide-Pentabromide

328

Equilibrium in the Counteranion of the Ionic Intermediates. J. Org. Chem. 1992, 57 (24),

329

6474–6478.

330

(22)

Bellucci, G.; Roberto Bianchini, S.; Chiappe, C.; Ambrosetti, R. Formation of

331

Pentabromide Ions from Bromine and Bromide in Moderate-Polarity Aprotic Solvents and

332

Their Possible Involvement in the Product-Determining Step of Olefin Bromination. J .

333

Am. Chem. SOC 1989, 1 (1), 199–202.

334

(23)

Wang, T. X.; Kelley, M. D.; Cooper, J. N.; Beckwith, R. C.; Margerum, D. W.; June, R.

335

Equilibrium Kinetic and Uv Spectral Charac of Aque Bromine Chloride-Bromine-and

336

Chlorine Species. Inorg. Chem. 1994, 33 (25), 5872–5878.

337

(24)

Interscience publication, 1988.

338 339

Kinoshita, K. Carbon: Electrochemical and Physicochemical Properties; A Wiley-

(25)

Pegis, M. L.; Roberts, J. A. S.; Wasylenko, D. J.; Mader, E. A.; Appel, A. M.; Mayer, J.

340

M. Standard Reduction Potentials for Oxygen and Carbon Dioxide Couples in Acetonitrile

341

and N , N ‑ Dimethylformamide. Inorg. Chem. 2015, 54, 11883–11888.

342

(26)

Mitsuda, K.; Murahashi, T. Air and Fuel Starvation of Phosphoric Acid Fuel Cells: A

343

Study Using a Single Cell with Multi-Reference Electrodes. J. Appl. Electrochem. 1991,

344

21 (6), 524–530.



345

(27)

Cohen, I.; Avraham, E.; Bouhadana, Y.; Soffer, A.; Aurbach, D. The Effect of the Flow-

346

Regime, Reversal of Polarization, and Oxygen on the Long Term Stability in Capacitive

347

de-Ionization Processes. Electrochim. Acta 2015, 153, 106–114.

348


Page 18 of 25

Page 19 of 25

349


Fig. 1.

350 Solution outlet

PVC upper cover Current collector 5 X Activated carbon cloth electrodes Spacer (polytetrafluoroethylene) Separator One activated carbon cloth electrode Ag/AgCl Reference electrode mesh Water dispenser PVC bottom cover

351 Solution inlet

352 353

Fig. 1. Illustration of the flow-through HPA-CDI cell used in this study.

354

Fig. 2.

355 356

Fig. 2. Illustration of the HPA-CDI experimental setup used in this study.

357



358

Fig. 3.

359 360

Fig. 3. Cyclic voltammetry plots created by a three-electrode system, where the y axis

361

represents the capacitance (F/gr) and the x axis represents the applied potential in

362

reference to a saturated Hg/HgCl electrode (SCE). The scan rates and concentrations of

363

both NaCl and NaBr solutions are 1 mV/sec and 0.05 M, respectively. The NaCl solution

364

preserves its capacitive behavior even at high potential of 1 V, where a small rise in water

365

splitting can be seen. On the other hand, the NaBr solution preserves capacitive behavior

366

until the high vortex potential reaches 0.8 V, above which it displays electrochemical

367

redox behavior.

368 369 370 371 372


Page 20 of 25

Page 21 of 25


373 374

Fig. 4.

375 376

Fig. 4. Cyclic voltammetry plot, where the y axis represents the capacitance (F/gr) and

377

the x axis represents the applied potential in reference to saturated Hg/HgCl electrode

378

(SCE). A mixed solution of NaCl and NaBr in concentrations of 0.05 and 0.005 M,

379

respectively, was prepared and used in a three-electrode system, where the NaCl salt was

380

used as a supporting electrolyte. Two different scan rates were used: the 1 mV/sec scan

381

rate preserved capacitive behavior in the cathodic side, and at high potentials gave an

382

oxidation peak in the anodic polarization; the 0.5 mV/sec scan rate preserved capacitive

383

behavior between -0.1 and 0.5 V, with a working potential domain for the redox

384

electrochemical reaction between 0.5 and 1 V.

385



386

Fig. 5.

387 388

Fig. 5. Plot of salinity of a mixed solution of NaCl and NaBr, in molar units vs. time,

389

measured during the last three of five cycles of operation by an HPA-CDI cell. The

390

starting concentrations of both NaCl and NaBr were 0.05M. Samples were taken at time

391

intervals of five minutes from the solution outlet of the cell for ex-situ analysis to first

392

separate between the chloride and bromide ions by ion chromatography and afterword the

393

amount of ions were quantified by titration with silver nitrate. The plot shows a specific

394

removal and recovery of bromide ions from a mixed solution that initially contained the

395

same concentration of ions. The samples from the three cycles were taken after two

396

preliminary cycles that were carried out in order to achieve proper steady-state operation

397

of the electrodes.

398 399


Page 22 of 25

Page 23 of 25

400


Fig. 6.

401 402

Fig. 6. Plot of current against time for a mixed solution of NaCl and NaBr, where both

403

concentrations were initially 0.05 M, measured during the last three of five cycles of

404

operation by an HPA-CDI cell. The repetition in the three cycles gives another indication

405

of the consistency of the results, from the aspect of the electric charge.

406



407

Fig. 7.

408 409 410

Fig. 7. Column chart of accumulated amounts of bromide and chloride ions, which were

411

removed and recovered, in mmol/gr units, normalized by the total weight of the ACC

412

working electrodes, during the last three of five cycles of operation by the HPA-CDI cell.

413

The chart shows that the accumulated removal and recovery of bromide ions in each

414

cycle were nearly the same, almost two orders of magnitude higher with respect to

415

chloride ions.

416


Page 24 of 25

Page 25 of 25

417


Abstract Art (TOC)

418


Bromide Ions Specific Removal and Recovery by Electrochemical

Recommend Documents