Research Article Simultaneous Recovery of Hydrogen and Chlorine...

Research ArticleSimultaneous Recovery of Hydrogen and Chlorine fromIndustrial Waste Dilute Hydrochloric Acid

N Paidimarri1 U Virendra2 and S Vedantam2

1Department of Chemical Engineering Birla Institute of Technology and Science Pilani Pilani Rajasthan 333031 India2Chemical Engineering Division CSIR-Indian Institute of Chemical Technology (IICT) Hyderabad Telangana 500007 India

Correspondence should be addressed to S Vedantam spriyavedantamgmailcom

Received 30 December 2015 Accepted 23 March 2016

Academic Editor Donald L Feke

Copyright copy 2016 N Paidimarri et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Recovery of chlorine from byproduct HCl has inevitable commercial importance in industries lately because of insufficientpurity or too low concentration to recycle it Instead it is being neutralized in industries before disposing to meet stringentenvironmental conditions Although recovery through catalytic oxidation processes is studied since the 19th century their highoperating conditions combinedwith sluggish reaction kinetics and low single pass conversionsmake electrolysis a better alternativeThe present motive of this work is to develop a novel electrolysis process which in contrast to traditional processes effectivelyrecovers both hydrogen and chlorine from dilute HCl For this an electrolytic cell with an Anionic Exchange Membrane hasbeen designed which only allows the passage of chlorine anions from catholyte to anolyte separating the gasses in a single stepThe catholyte can be as low as 359wt because of fixed anolyte concentration of 199wt which minimizes oxygen formationPreliminary results show that the simultaneous recovery of hydrogen and chlorine is possible with high conversion up to 98Themaximum current density value for 496 cm2 membrane surface area (70 active surface area) is 254 kAmminus2 which is comparablewith reported commercial processes This study is expected to be useful for process intensification of the same in a continuousprocess environment

1 Introduction

Industrially generated hydrochloric acidhydrogen chlorideis often byproduct of chlorine consuming process such aschlorination of organic compounds Around 90 of HClproduced in US is byproduct of chlorination [1] The openmarket of HCl is very less and most of the HCl produced iseither productively used by the producer or put to local use(domestic local industry) The industrially produced HCl isgenerally up to 38wt concentration higher concentrationsare expected to cause vapour losses The byproduct HClproduced has many uses depending upon concentration allthe uses are summarized in Scheme 1 But this byproduct HClneeds to be treated for trace amounts of impurities before it isput to use which increases operational costs It is not alwayspossible to locate use for dilute HCl produced and shipping itto over large distances is not an economically lucrative optionIn general market for HCl is saturated and does not growas necessary [2] and open market for HCl as said earlier isvery less So the excess dilute HCl is traditionally neutralized

before disposing without its effective utilization it is quitecomprehendible to note the expense of neutralization whichin turn increases the quantity of waste and also large amountof potential chemicals is lost The quantity of HCl whichwas neutralized in Germany in 1995 because no option forreuse was available is 230000 ton HCl [3] The option ofevaporating may look as a feasible alternative for producingconcentrated HCl from dilute but with evaporation the HClconcentration cannot be increased more than a certain valuebecause of HCl boiling point being very less in comparison towater Through distillation high purity HCl can be recoveredfrom water but the major problem would be high energydemand and need to use exorbitant metals when usingconcentrated HCl at high temperatures

Chlorine is no doubt one of the most important basechemicals in industry to produce many useful productsBeing a halogen group element it is a very strong oxidizingagent Hydrogen on the other hand has many uses it is therichest fuel in terms of calorific value and its demand increas-ing from day to day especially in developing countries as the

Hindawi Publishing CorporationInternational Journal of Chemical EngineeringVolume 2016 Article ID 8194674 13 pageshttpdxdoiorg10115520168194674

2 International Journal of Chemical Engineering

Byproduct HCl

Calcium chloride Laboratory acid

Oil well

Muriatic acidSteel pickling

Domestic cleaning

36wt

10ndash12wt

15ndash18

wt

35

wt

5ndash35wt

20ndash30wt

Scheme 1 Uses of HCl recovered as byproduct [4ndash6]

demand for energy increases makes hydrogen important It isalso said that hydrogen being a clean fuel will be the sourceof energy in future So recovery of hydrogen and chlorine isbeing inevitably important industrially as time progresses

The market price of HCl can be under pressure becausethe expansion in demand for vinyl chloride monomers (mainrawmaterial isHCl) is smaller [7] Additionally since chloral-kali is the main route for producing chlorine industrially andthe expansion of the demand for chlorine (annual productionof Cl2globally is 58MMT [8] and has an expected demand

growth of 44 per year since 2010 [9]) is greater than thatof the demand for the caustic soda (NaOH) main product ofchloralkali process there is a danger that the demand balancebetween Cl

2and NaOHwill collapse [7] So it is important to

develop technologies for recovering chlorine and hydrogenfrom HCl and reutilizing it which can decrease the amountof excess HCl expected in market and also will balance thedemand of chlorine in market

Initially many processes are developed to recover chlo-rine like electrolysis (UHDE ODC) and catalytic oxidation(MT-Chlor) Although the recovery of chlorine from HClis being studied for more than 100 years the recovery ofboth hydrogen and chlorine is nevertheless studied less incomparison With this in background current study reportssimultaneous recovery of chlorine and hydrogen from indus-trial waste using batch electrolysis process An attempt hasbeen made to study the effect of various parameters whichaffect the conversion significantly The results and discussionare mainly focused on 2N (708wt) and 4N (1373 wt)because the industrial waste HCL generally is up to 20wt[10]

The recovery of hydrogen and chlorine if developed willhavemuch scope for application industrially One such exam-ple is phosgene mediated isocyanate production of TolueneDiisocyanate (TDI) the reactions shown below depict theprocess

CO + Cl2997888rarr COCl

2 (1)

CH3C6H3(NH2)2+ 2COCl

2

997888rarr CH3C6H3(NCO)

2+ 4HCl

(2)

For every 1 mole of TDI 4 moles of HCl is produced asbyproduct Approximately half of the Cl

2produced annually

is estimated to end up as HCl byproduct generated in the waydescribed above or as various other chlorides [7] So HCleither is a direct byproduct or is also produced when chlorineis removed in order to obtain chlorine-free products

Considering the concerns mentioned above with treatingindustrially waste dilute HCl it is a motivation to work onrecovery of both hydrogen and chlorine from waste diluteHCl from industries using electrolysis One of the mainadvantages of electrolysis is that it is a low temperature andpressure process and it can be monitored easily compared tooxidation processes

Different industrial recovery processes are explained inTable 1 Table 1 mainly summarizes two processes catalyticoxidation and ion exchange electrolysis The catalytic oxida-tion processes areDeaconKel-Chlor Shell-ChlorMT-Chlorand Sumitomo none of these processes recover hydrogen(it is lost as water) Out of these Kel-Chlor and Shell-Chlor are said to be commercialized but they are notoperational now only MT-Chlor and Sumitomo processesare commercially being used at present Even though catalyticoxidation processes are said to consume less energy the maindisadvantage is that they operate above 250∘C and productpurification involvesmultiple steps if feed conversions are less(even assuming 66 conversion the effluent has only 33Cl2) In contrast electrolysis is low temperature operation

and it is possible in few configurations (UHDE diaphragmand DuPont gas phase electrolysis) to recover both hydrogenand chlorine UHDE ODC is very much being licensedbecause of low energy consumption Table 2 summarizesresearch studies on recovering chlorine from HCl As can beseen the literature also reports similar electrolytic processeshowever studies on simultaneous recovery of both chlorineand hydrogen have not been many Moreover reportedstudies have been carried out for several hours of operationwhich do not seem to be economical Hence it is thoughtdesirable to work on the effect of different parameters affect-ing the electrolytic process However the other advantagesof recovering hydrogen and chlorine also include making theplant economics independent of both hydrogen and chlorine

International Journal of Chemical Engineering 3

Table1Indu

stria

lprocesses

ofchlorin

erecovery

Author

Process

Reactio

nMetho

dology

Con

clusio

nsRe

marks

Benson

andHish

am[11](19

92)

Deaconprocessd

evelop

edby

Henry

Deaconin

1868

[11]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Dire

ctoxidationarou

nd425to

475∘C[11]in

presence

ofcopp

ercatalyst

(ii)E

xothermicprocessh

asinterm

ediatereactio

nsresulting

inslu

ggish

reactio

nkinetic

s

(i)Lo

wer

yields

becauseo

flow

conversio

nandcatalystactiv

ity[12]

(ii)C

onstr

uctio

nisexpensive

duetohigh

lycorrosive[11]

interm

ediates

(i)Sing

lepassconversio

nsarou

nd60to

80

(ii)C

atalystactivity

decreasesa

bove

402∘C

becauseo

fvolatilizatio

n[9]

(iii)Never

been

putto

commercialuse[1213]

And

oetal[7]

(2010)

Kel-C

hlor

byKe

llogg

inthe1960s

[14]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Oxidatio

nusing

nitro

genoxides

asthe

catalystandsulphu

ricacid

ascirculatingmedium

[7]

(i)Needs

expensivep

lant

desig

nandsafetyfeatures

becauseo

fmanyinterm

ediatereactio

nste

ps[711]m

akingiton

lypo

ssiblefor

large-scalep

lants

(i)Needs

extensive

downstre

amprocessin

gto

getp

urec

hlorine

(ii)D

uPon

tstarted

20000

0ton

yearp

lant

in1974but

itisno

toperatin

gatpresent[7]

Engeland

Wattim

ena[

15](1965)

Shell-C

hlor

byShell

patented

in1965

[15]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Oxidatio

nin

fluidized

bedprocessat300

to425∘C

(ii)C

atalystisc

ompo

sedof

copp

erchloriderare

earth

materials

andothersat

determ

ined

ratio

[15]

(i)Highcatalystactiv

itybecause

oflowvolatilization

(ii)C

orrosio

nisalso

less[15]

(i)Con

versionof

80can

beachieved

[15]

(ii)S

hellop

erated

afacility

of30000

tyrinthe1970s

[13]but

operationwas

eventuallyshut

down

ThyssenK

rupp

[2]

UHDEdiaphragm

process

developedby

Bayer

MaterialScience

ampUhd

enora

Ano

de

2Clminusrarr

2Cl 2+2eminus

Cathod

e2H++

2eminusrarr

H2

(i)Aq

ueou

selectrolysis

processu

singPV

CPV

DF

diaphragm

at65

to70∘C

[2]

(ii)G

raph

iteelectro

desa

reusedW

ater

transfe

r(osm

aticdrag)isp

resent

(i)Gas

purityislim

itedbecause

thed

iaph

ragm

cann

otim

pede

gasd

iffusioncompletely

[3]

(ii)M

inim

umHCl

concentrations

shou

ldbe

maintainedto

avoidoxygen

evolution[3]

(i)Th

econ

versionis25

(23to

17wt

)(ii)P

ower

consum

ptionis

1670

kWhtminus1Cl2at5k

Amminus2

[2]

(iii)In

Germanyin

1995

20of

theH

Clprod

uced

was

recycle

dthisway

[3]

Itohetal[16](1989)

MT-Ch

lorb

yMitsui

Toatsu

patented

in1989

[16]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Oxidatio

nin

fluidized

bedprocessu

singCr2O3sdot

SiO2catalyst[7]in

presence

ofpu

reoxygen

[16]

at300∘ndash500∘C

(i)UnlikeD

eaconhere

catalyst

operates

with

outm

eltingso

the

stabilityof

thec

atalystisg

reatly

improved

[7]

(i)Con

versions

upto

80

canbe

achieved

[16]

(ii)O

mutas

ince

1988

has

60000

tycapacityplant

operatingsuccessfu

lly[7]

Trainh

ametal[17](1995)

DuP

ontgas

phase

electrolysis

byDuP

ontd

eNem

ourspatented

in1995

[17]

Ano

de2HCl

(g)rarr

Cl2(g)+

2H+(aq)

+2eminus

Cathod

e2H+(aq)

+2eminusrarr

H2(g)

(i)SimilartoCE

Mele

ctrolysis

processb

utoccursin

gasp

hase

throug

hgasd

iffusiontype

mem

branes

(ii)Th

eelectrolyseris

operated

at450ndash

550k

Paand70ndash9

0∘C

(i)NoHCL

absorptio

nste

p(ii)S

impled

ownstre

amprocess

issufficientfor

purifi

catio

nbecausefeedisanhydrou

s[14]

(iii)Water

transport(osmatic

drag)isp

resent

(i)HCl

conversio

nratio

upto

85[7]can

beachieved

becauseo

fhighdiffu

sion

coeffi

cients(gas

phase)[14

](ii)P

ower

consum

ptionat

5kAmminus2isroug

hly

1120

kWhtCl 2[14

]


Table1Con

tinued

Author

Process

Reactio

nMetho

dology

Con

clusio

nsRe

marks

Iwanagae

tal[13]

(200

4)

Sumito

moprocessb

ySumito

moCh

emicalCo

Ltddevelopedin

2000

[13]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Oxidatio

nprocessin

fixed

bedreactoru

sing

RuO2TiO2(rutile)catalyst

Canbe

operated

aslowas

250∘C

(ii)Th

isprocessh

ashigh

erconversio

nsbecauseo

ffix

edbedreactor

(i)Th

iscatalysthash

igher

activ

ityandthermalstability

than

theo

nesd

iscussedabove

[13]

(ii)S

ince

2003

aplant

having

prod

uctio

ncapacityof

10000

0ty

isop

eratingsm

oothly

(i)Con

versions

upto

95

arep

ossib

le[13]

(ii)P

ower

consum

ptionis

165k

Whtminus1Cl2[13]

which

isvery

lessincomparis

onto

Bayer-DENoraP

rocess

butn

ocomparis

onsfor

capitalcostsarer

eported

ThyssenK

rupp

[2]

UHDEODCprocess

developedby

Bayer

MaterialScience

ampUhd

enora

Ano

de4HCl

(aq)rarr

4H++4eminus

+2C

l 2Ca

thod

e4H++

4eminus+O2rarr

2H2O

(i)SimilartoCE

Melectro

lysis

processbu

thydrogen

generatio

nis

supp

ressed

bywater

form

ationresulting

in30

saving

sinele

ctric

consum

ptionandvoltage

lessthan

1V[2]

(i)Water

transportisp

resent

from

anod

etocathod

e(ii)M

anyplantslatelylicensin

gthistechno

logyfor

exam

ple

Bayerstarted

operatinga

commercialplanto

f215000

tyr

[7]

(i)Th

epow

erconsum

ption

is1070

kWhtminus1Cl2at

5kAmminus2thatislessthan

diaphragm

processbu

tthe

capitalcostsforthe

same

aren

otrepo

rted


Table 2 Research studies on chlorine recovery

Author Methodology Main parametersrsquo effectsdiscussed Conclusions Remarks

Johnson andWinnick [18](1999)

(i) An AEM process is developedfor recovery of chlorine fromgaseous HCl but here chlorideions migrate across the moltensalt electrolyte saturatedmembrane

(i) In free electrolyte (nomembrane) trialsconversion and currentefficiency were determinedas a function of currentdensity required cellvoltage and feed gas flowrate(ii) At single-cellmembrane cross cellpotentials at different feedrates are studied

(i) This study shows thatelectrochemical membraneseparation is a feasiblealternative for the removalof chlorine from HCl atreasonable voltages highconversion

(i) This paper ismore of afeasibility study(ii) Nothing inregard to powerconsumption orprocesseconomics issaid

Vidakovic-Koch etal [10] (2012)

(i) Polymer electrolytemembranes have broadapplications in this reviewemphasis is upon the applicationof Nafion membranes forchlorine recycling

(i) The Nafion membranehas role of a separator and asolid electrolyte(ii) Proton transportmechanical stability ofmembrane and influenceof dispersion medium andits relevance for formationof ion conducting networkare studied

(i) Nafion performance isstudied in the range of18 wt to 20wt HCl(ii) Nafion performance isimportant for reactoroptimization

(i) This reviewstudy onlyconsidersNafionmembranesperformanceand no referenceis made toprocesseconomics

Barmashenko andJorissen [3] (2005)

(i) An AEM process is developedfor recovery of hydrogen andchlorine from dilute HCl toovercome the limitations of CEMprocess(ii) The results are shown withalternative designs to overcomeits limitations (EOD)

(i) Parameters likeselectivity of membraneand current efficiencieswith respect to CaCl

2

concentration and cellvoltage are discussed(ii) Voltage drop versuscurrent density and watertransfer through membraneis also considered(iii) A possible design foran AEM with empty (gasfilled) anode chamber ispresented

(i) This paper reviewedalmost all electrolysisprocesses developed till2005(ii) They were able toperform AEM process withcathode concentration aslow as 32 wt

(i) The energyrequirement is1740 kWh at4 kAmminus2 andcell voltage of23 V(ii) Effects ofmembranesurface areaelectrodesurface areaand temperatureof the system arenot consideredProcesseconomics is notstudied in detail

Mazloomi et al[19] (2012)

(i) This paper tries to studyparameters which affect electricalefficiency of KOH electrolysis tooptimize electricity expensewhich is a majority inelectrolysis

(i) Total electrical efficiencyis divided into threeseparate factors electricalresistance electrolysis andthermal efficiency(ii) Temperature pressureand resistance ofelectrolyte alignment ofelectrodes electrodematerial and appliedvoltage waveform arestudied

(i) This paper does notexactly deal with AEMelectrolysis but the natureof the parameters mightremain the same to someextent in all electrolysisprocesses

(i) Almost all ofthe parametersstudied are onlyon KOHelectrolysis(ii) This studyonly focused onelectricalefficacy

Koter andWarszawski [20](2000)

(i) Electrodialysiselectro-electrodialysis andmembrane electrolysis arediscussed along with theirapplications to reduceenvironmental impact

(i) A great deal regardingion exchange membranes isdiscussed like applicationof membranes in fuel cellsMembranes (Nafion)properties are alsodiscussed

(i) Concludes that ionexchange processes aremore sustainable andcleaner technologies incomparison to otherrecovery processes

(i) This paper ismore of a reviewstudy formembraneelectrolysis(ii) Economicaspects are notdiscussed indetail


Table 2 Continued


Ando et al [7](2010)

(i) This RampD report of SumitomoChemical Co Ltd mainly dealswith newly developed rutile-typecatalyst for oxidation of diluteHCl and also considers energyeconomics

(i) Performance of rutilecatalyst is determined incomparison to othercatalysts based onconversion corrosionresistance and stability(ii) Complete overview ofthe process is presented

(i) Rutile-type catalystsconsume very less energycompared to UHDE ODCprocess(ii) The paper also reviewsall recovery processes in theliterature

(i) Although itsays that rutilebased catalyticoxidation isbetter thanelectrolysis itdoes not recoverhydrogen(ii) Directcomparison ofcapital andoperating costswith UHDE isnot reported

market prices As is well known transportation of hydrogenhas always been an expensive operational cost

With this in the background andmotivation the objectiveof the current work has been to simultaneously recoverhydrogen and chlorine from industrially wasteHCl and studythe effect of parameters such as time of operation conversionelectrode distance current density feed concentration andcurrent efficiency which are presented in the followingsections

2 Materials and Methods

Considering the wide scope of work in this field as initialstage current work has been confined to batch processSchematic of the experimental setup can be viewed inFigure 1 The system consists of cathode and anode cham-bers separated by an Anionic Exchange Membrane (AEM)typically used for gas separation AEM is chosen over CEM(Cationic Exchange Membrane) because in case of CEM theconversion is observed to be less and CEM membranes aregenerally more expensive [3]

Both cathode and anode chambers have a capacity of30mL separated by AEM Catholyte comprised feed solutionof HCl while the anolyte is fixed to very dilute 055N(199wt)HClwith added salt in order to aid as an electrolytein ion movement Different electrodes such as tin titaniumand stainless steel have been attempted but since they yieldedto corrosion due to the presence of HClchlorine platinumwire electrodes were used It is to note that in spite of usingthese electrodes for more than 200 total experimental hoursno corrosion was observed The membrane surface area forall the experiments has been 7068 cm2

All samples have been analysed based on standard acid-base titration methods Hydrogen is collected based onthe downward displacement of water technique by passingthrough an inverted measuring cylinder filled completelywith water Mass balances have been established for all theinflow and outflow materials Chlorine is bubbled into abubbler filled with potassium iodide (KI in water) solutionand analysed using iodometry one of the best known

analytical methods for estimating chlorine Iodometry usessodium thiosulphate as titrant Chlorine determination usingiodometry involves two steps firstly the chlorine is bubbledthrough potassium iodide solution displacing iodine andforming potassium chloride Now the liberated iodine formsa complex with potassium iodide which is dark brown incolour it was made sure that the solution contained excessKI such that chlorine losses are minimized As is well knownthe following reactions take place

2KI (aq) + Cl2(aq) 997888rarr 2KCl (aq) + I

2(aq) (3)

I2(aq) + KI (aq) 997888rarr KI

3(aq) (Dark Brown) (4)

The standardization of sodium thiosulphate and titration ofKI3should be conducted at certain predetermined procedure

to avoid errors and unwanted reactions Iodometry is a well-known procedure for determining chlorine quantity andmany open sources are available it has some limitationsregarding the molar concentrations of chlorine and these arealso reported in the literature While establishing materialbalances additionally simultaneous water electrolysis andwater transport through the membrane are also taken intoaccount All experiments are performed at ambient condi-tions

3 Results and Discussions

As per the procedure explained in previous section exper-iments were carried out for simultaneous recovery of chlo-rine and hydrogen Most of the analysis presented here isexplained in terms of the conversion (from here onwardstermed as CE) and charge generated as these are the mostimportant objectives of this entire research work Furtherexperiments were carried out at different conditions by vary-ing each parameter at a time keeping the others unchangedThe parameters considered for the study of CE and totalcharge generated are feed catholyte concentration electrodepotential time of operation electrode distance (ED) andcurrent efficiency


Voltage regulator

Cathode chamber Anode chamber

(1) Platinum electrodes(2) Rubber stoppers(3) Anionic Exchange Membrane

31

2

1

2

H2

Clminus

H2O

2eminus 2eminus

Cl2

2H+rarrH2

2Clminus rarrCl2

Figure 1 Schematic of the experimental setup used for batch electrolytic process of hydrochloric acid

Conversion simply put forward is the percentage of feedelectrolysed and it is determined by estimating the finalconcentration of catholyte after the electrolysis estimatedbased on titrimetry it is to note that the conversion is simplythe percentage of feed HCl that got electrolysed Thus

Conversion

= 100

lowast (1 minus (

Final Catholyte ConcentrationInitial Catholyte Concentration

))

(5)

The term total charge generated is the total amount of currentthat passed through the solution due to the ion movementcaused by the electrolytic process or the total amount ofcurrent that is generated by the solution when subjected to acertain voltage Total charge values are mentioned in amperehours

Total charge = sumCharge generated lowast Time (6)

Total charge value is a quantitative measure of ions passingthrough anion exchange membrane so if more numbersof ions are passing it implies that more of the feed iselectrolysed so we can say that CE and total charge aredirectly proportional although the exact relation dependson other parameters (such as electrode distance time ofoperation electrode potential and ionic movements of thesolution) Figure 2 depicts a graph of total charge generatedagainst CE for 4N and 2N (here ldquoNrdquo refers to normality= equivalentsm3) initial feed concentrations at electrodepotential of 16V It can be seen that the curve is linear withtotal charge increasing with increase in CE

31 Chlorine Recovery Chlorine is estimated quantitativelyusing iodometry Chlorine solubility in water is estimatedbased on Figure 3 [21] it can also be calculated from [22]at the temperature during experimentation The free iodinesolubility in water is very less hence as soon as iodine

0

04

08

12

16

2

24

28

32

36

4

0 10 20 30 40 50 60 70 80 90 100

Tota

l cha

rge (

ampe

re h

ours

)

Conversion percent (mdash)

40N20N

Figure 2 Conversion percent (mdash) versus total charge (amperehour)

is displaced by chlorine it forms the complex Chlorinerecovery percentage is calculated based on

Chlorine recovery

=

Amount of Chlorine capturedChlorine amount to be captured

lowast 100

(7)

Figure 4 depicts typical recoveries at different feed catholyteconcentrations Recoveries greater than 100 can beobserved because the ambient temperature during thecourse of the electrolysis reached as high as 48∘C for fewdays such that the solubility of chlorine in water could


Water temperature (Celsius)

Chlo

rine s

olub

ility

(gm

kg

wat

er)

10

9

8

7

6

5

4

3

2

1

0

0 20 40 60 80 100

Figure 3 Chlorine solubility in water

0

10

20

30

40

50

60

70

80

90

100

110

120

130

0 1 2 3 4 5 6 7 8 9 10

Chlo

rine r

ecov

ery

perc

ent (

mdash)

Feed cathode concentration (normality)

Figure 4 Chlorine recovery percent (mdash) versus feed catholyteconcentration (normality)

have been even less than 44 kgm3 This smaller change insolubility alters the recovery up to a range of 20

Chlorine material balance has been established in orderto calculate the amount of chlorine recovered Herein theamount of chlorine to be captured refers to the decreasein the amount of chlorine present within catholyte (in theform of HCl) Total amount of chlorine captured compriseschorine determined from the iodometry of bubbler solutionchlorine from solubility of chlorine in bubbler solution andfinally chlorine residual in anolyte which is determined usingiodometry by adding small amount of KI

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Hyd

roge

n re

cove

ry p

erce

nt (mdash

)


Figure 5 Hydrogen recovery percent (mdash) versus feed catholyteconcentration (normality)

32 Hydrogen Recovery Hydrogen recovery is calculated as

Hydrogen Recovery

=

amount of Hydrogen capturedHydrogen amount to be captured

lowast 100

(8)

The hydrogen is collected using downward displacement ofwater Figure 5 shows the recovery of hydrogen at differentfeed concentrations Though downward displacement ofwater technique is very accurate because it does not involveany reactions and no titrations are required to estimate it thevolume of electrolysis cell chambers is only 20mL hence even01mL error attributes to around 5 difference in hydrogenrecovery values These values are only approximations witherrors up to 5

Before detailing on hydrogen material balance twoimportant phenomena are to be discussed simultaneouswater electrolysis and electroosmotic drag that occur duringthe electrolysis process Water electrolysis is quite possiblebecause the minimum voltage required for water electroly-sis is 123V theoretically around 185V with overpotentialresistances [23] Since the current work has been carried outaround 16V water electrolysis is expected so the amountof hydrogen captured was always observed to be greaterthan the amount of hydrogen decrease in catholyte Theother phenomenon is electroosmotic drag [3] (from hereonwards termed as EOD) As chlorine anions pass throughthe membrane water molecules surrounding the anion alsotry to pass through the membrane and water transportis additionally supported by diffusion due to higher waterconcentration in the catholyte compared with the anolyte(wherein the salt is added) So there is always a decreasein catholyte volume in the end because of water electrolysisand EOD whereas there is an increase in the anolyte volume


Table 3 Minimum voltage required for different feed concentra-tions

Feed cathodeconcentration(normality)

Electrode distance(cm)

Minimum voltage(V)

4 14 172 14 234 72 152 72 16

due to EOD Figure 6 shows EOD for 4N experimentsEOD increases as conversion increases due to increase in thequantity of chlorine anions passing through membrane Thevolume of water electrolysed is determined by subtracting thevolume gain in anolyte from volume decrease in catholyte

Similar to that of chlorine hydrogen material balanceis established to calculate hydrogen recovery The amountof hydrogen to be captured is the quantity of hydrogendecreased in catholyte and hydrogen formed through waterelectrolysis (see (9)) Amount of hydrogen captured is simplythe value calculated from real gas law where the volume isvolume of hydrogen captured using downward displacementof water technique

2H2O + 2eminus 997888rarr H

2+OHminus (9)

33 Feed Catholyte Concentration The effect of initial con-centration is mainly studied at 16V 4 hrs of electrolysisand ED of 014m for 2N (708wt) 4N (1373 wt) and6N (20wt) with at least three different experimental runsperformed to check reproducibility conversion values canbe seen in Figure 7 Effect of parameters in the followingsections is presented for 2N and 4N experiments onlybecause experiments were also carried out with higherconcentrations of HCl (such as 8N (2596wt)) but it wasobserved that the temperature increased to nearly boilingpoint of HCl the anolyte started to boil and these liquiddroplets began to move out along with chlorine This couldbe even due to the very small batch size considered Howeverdetailed experimentationwas not continuedwith such higherconcentrations since most industrial waste HCl is nearly 17ndash20 or lesser On the other side even at lower normalityrise in temperature was noticed but was just not sufficientto boil the anolyte Moreover current study is confined todealing with industrial waste HCl hence further detailedexperimentations on 6N and 8N were not done

34 Electrode Potential Difference In an electrolysis processvoltage applied plays a crucial role because power is themajoroperating cost of the process An attempt to study the effectof voltage on 2N and 4N has been carried out Figure 8shows the effect of voltage on CE and total charge for a2N feed catholyte concentration solution subjected to 4 hrsof electrolysis at an ED of 0072m CE increases as voltageincreases but the slope of increment decreases after 16Vthe slope is increasing clearly after 12V and then reduceswhen it reaches 16V So it can be inferred that 14V and 16V

0

1

2

3

4

5

0 10 20 30 40 50 60 70 80 90 100

EOD

(mL)


4N

Figure 6 Electroosmatic drag (mL) versus conversion (mdash)

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Con

vers

ion

perc

ent (

mdash)


Figure 7 Conversion percent (mdash) versus feed cathode concentra-tion (normality)

are most suitable to work with to get optimum conversionExperiments conducted for voltages above 20V led to anincrease in temperature of the entire reaction chamber Fromthe above discussions it was decided to work with 16VFigure 9 shows the effect of voltage for the experimentsconducted with 4N feed concentration for the same EDThesame can be inferred from Figure 9 that is 14 V and 16V areoptimum choices In both feed concentrations the nature ofgraphs remains the same To minimize cell voltage which isthe main factor influencing the specific energy requirement


0

03

06

09

12

15

18

21

24

27

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20To

tal c

harg

e (am

pere

hou

rs)

Voltage (volts)

ConversionTotal charge

Con

vers

ion

perc

ent (

mdash)

Figure 8 Conversion percent (mdash) and total charge (ampere hour)versus voltage (volts) for 2N feed concentration

many parameters are being considered for further studiessome experiments are performed to determine theminimumrequired cell voltage these results can be seen in Table 3Minimum voltage is required for different feed concentra-tionsTheminimum required voltage is considered as voltageat 0001 amp As ED decreases the resistance offered toionic movement decreases and this explains the decrease inminimum required voltage

35 Time of Operation The reported literature had indicatedthat most electrolysis experiments of HCl have been con-ducted for long hours of operation to study the effect ofparameters Since this work has been initiated with an objec-tive of recovering chlorine and hydrogen simultaneously suchthat the entire operation could be made self-sufficient interms of energy consumption it was thought apt to studythe effect of time of operation Further time of operationbecomes a very crucial parameter when the batch systemwould have to be scaled to continuous system The time ofoperation is examined by taking intermediate samples forevery hour Figure 10 shows that curve becomes flat after 3hours (89 CE till 3 hours) for 4N experiment and after 2hours for 2N (9079 CE in 2 hours)

36 Electrode Distance (ED) ED plays a significant role onvariation in CE because the lesser the value of ED the morethe surface area of electrode that is available thus increasingthe number of ions generated every time instance therebyincreasing the ionic movements across the membrane Andalso by decreasing the ED the resistance is reduced because ofthe decrease in distance to be travelled by ions Experiments

0

04

08

12

16

2

24

28

32

36

4

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20

Tota

l cha

rge (

ampe

re h

ours

)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)

Figure 9 Conversion percent (mdash) and total charge (ampere hours)versus voltage (volts) for 4N feed concentration

were performedmainly maintaining two different ED 014mand 0072m Figures 11 and 12 show CE at different ED fortwo feed concentrations it can be seen that both graphs havesimilar nature We can see that as ED increases the CE aswell as total charge decreases Further reduction in ED wasnot performed since almost 97-98 electrolysis was alreadyobtained To study the parameters which contributedmore toincreased conversion for reduction in ED some experimentswere performed by bending the electrodes For instance theelectrodes initially were placed at 0072m and they were benttill the tips are at distance of 014m by this we increasedthe surface area of electrodes without changing the electrodedistance The conversion for 4N feed concentration at 16Vfor increased surface area is 4636 which is almost thesame as the conversion at 0072m indicating that after allthe main dominating parameter is ED rather than increasedconcertation of ions (increased area of electrode) The samecannot be generalized without looking into more similarresults for different voltages and surface area of electrodes

37 Current Density Current density herein is defined asthe amount of current passing through unit surface area ofmembrane shown as follows

Current Density =Current being generatedMembrane Surface area

(10)

The membrane surface area has been constant to 7068 cm2but the active surface area while performing the experimentshas been only 70 (owing to the capacity of catholyte andanolyte chambers) with a surface area of 4946 cm2 Table 4shows maximum current values when operating at different


Table 4 Current density values for different feed concentrations and UHDE ODC process

ProcessFeed cathodeconcentration(normality)

Maximum chargegenerated (amperes)

Active membranesurface area (cm2)

Current density(kAmminus2)

AEM 2 113 49602 2283936AEM 4 126 49602 2546689AEM 2 113 7068 1598755AEM 4 126 7068 1782683UHDE ODC [2] 46 25000 5

0

05

1

15

2

25

3

35

4

45

0 1 2 3 4

Cath

olyt

e con

cent

ratio

n (n

orm

ality

)

Time of operation (hours)

40N20N

Figure 10 Catholyte concentration (normality) versus time ofoperation (hours) for 4N and 2N feed concentrations

normality for 16V and corresponding current density valuesin kAmminus2 The values at 4N for different active membranesurface areas are 254 kAmminus2 (assuming 70) and 178 kAmminus2(assuming 100) when comparing these with those reportedin the literature whose value is 5 kAmminus2 [2] at 25m2membrane surface area for 14wt (46N) feed concentrationwe can say that this method of AEM has high feasibility tobecome a better alternative in the future

38 Current Efficiency Electricity expense constitutes thelargest fraction of economics of electrolysis processes Highhydrogen production expenses is one of themain deficienciesof commercial and industrial electrolysers so the currentefficiency (sometimes referred to as Faradaic efficiency)[24] is determined by dividing the amount of current usedto convert hydrogen chloride to chlorine by total chargesupplied to the cell

120576current efficiency =119911 lowast 119899 lowast 119865

119876

(11)

0

05

1

15

2

25

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)

Figure 11 Conversion percent (mdash) and total charge (ampere hour)versus ED (mm) for 2N feed concentration

where 119911 is the number of electrons exchanged per mole ofthe electrolyte (here 119911 = 1) 119899 is the number of moleselectrolysed (here dilute HCl) 119865 is Faradayrsquos constant (119865 =96485Cmole) and 119876 is the total charge passed throughthe membrane in coulombs Figure 13 shows average currentefficiency values for 4N and 2N feed concentrations atdifferent voltages for ED of 0072m The average currentefficiency values are in range of 60 the remaining could bemajorly due to oxygen formationThe current efficiency givesan understanding on optimizing the performance of wholeunit withminimum electrical input andmaximum efficiency

39 Energy and Economic Efficiency The specific energyrequirement for the present study is not considered forcomparison with commercial processes because the experi-mentation is presently in batchmode and the efficiencywouldobviously be much less however it is felt needed to discussthe economic efficiency The calculated economicity andenergy efficiency for 16V and 4N were 7783 and 3566the costs assumed are for hydrogen 129 RsKg chlorine


0

05

1

15

2

25

3

35

4

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)

ConversionTotal current

Con

vers

ion

perc

ent (

mdash)


52 RsKg and electricity 4 Rsunit These costs vary fromplace to place and verymuch depend on localmarket demandand supply Economicity is simple ratio of revenue to costalthough only variable costs are considered these values areenough to depict the economic feasibility as variable costsare more important in the long run than fixed costs Energyefficiency is calculated by considering HHV (1418MJKg) ofhydrogen and dividing it by electrical energy input to thesystem (average current for 4 hrs 0837 amperes) Economicefficiency of 778 for a batch process seems commendablewhich will be definitely increased in continuous phase

4 Conclusion

Simultaneous recovery of chlorine and hydrogen from indus-trially waste hydrochloric acid has been carried out usingelectrolysis in an electrolytic cell as a batch process Intensi-fying this process to a continuous one will also be industriallysignificant and especially owing tominimal carbon footprintthe process can provide and maximize benefit it can offerto meet future energy demand As norms for environmentare expected to be more firm in the future this processwould prove to be an economical solution for companies andwith the advent of renewable energy the cost of electricitywould come down significantly in the long run The higheconomic efficiency of 90 for a simple batch process addsto commercial feasibility of this paper the process would bemore economical if scaled to continuous operation and thiswill be of great value addition to company in terms of energysavings and also mitigating the risk of environment impact

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18

Curr

ent e

ffici

ency

per

cent

(mdash)

Voltage (volts)

4N2N

Figure 13 Current efficiency percent (mdash) versus voltage (volts) forED of 0072m

The highlights of the entire paper are summarized asfollows

(i) The results of this paper confirm that simultane-ous recovery of hydrogen and chorine is feasiblewith electrolysis process using an Anionic ExchangeMembrane as separator The hydrogen and chlorinerecovery up to 90 is achieved

(ii) Fixing the anolyte concentration at 055N is provedto be effective by minimizing oxygen formation andat the same time use of platinum electrodes showedlong time durability

(iii) Total charge generated and conversion for a fixed feedcatholyte concentration are directly proportional tovoltage applied but the values increase less signifi-cantly after 16V

(iv) The electrode distance has a direct effect on theresistance of the process when electrode distances arereduced from014m to 0072m the conversion valuesincreased to 98 Such high single pass conversionsare not reported in the literature

(v) One of the main limitations is water transportthroughmembrane which continuously builds up thevolume of anolyte however this is not covered in thescope of this paper

(vi) The catholyte concentration decreases based on theextent of electrolysis but as for anolyte it wasobserved that with an increase in the conversion asthe ion movement increased osmatic drag increasealong with a reduction in anode concentration wasnoted


(vii) Current efficiency values shown are calculated onlyon basis of decrease in catholyte chlorine concentra-tion the values obtained are in range of 60

(viii) The current density value of 254 kAm2 is compa-rable to processes reported in the literature even atvery low membrane surface area and low feed con-centration of 1379wt makes this process a feasiblealternative in the future

(ix) The recovery of chlorine and hydrogen from wastedilute HCl using electrolysis is highly recommendedbecause not only it is possible to recover bothhydrogen and chlorine but also it is a sustainableprocess which decreases waste quantity by producinga clean fuel and highly demanding base chemical withminimum process steps

(x) It is resource conserving and has low environmentalimpact when compared to catalytic oxidation process

(xi) The high cost of platinum can be offset by coatingplatinum on surface of a cheaper base metal liketitanium

Competing Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] US Environmental Protection Agency Hydrochloric AcidJune 2015 httpwwwepagovttnchie1ap42ch08

[2] Hydrochloric Acid Electrolysis Sustainable Chlorine produc-tion ldquoThyssenKrupp Industrial Solutionsrdquo 2012 httpwwwthyssenkrupp-industrial-solutionscomfileadmindocumentsbrochuresHydrochloric Acid Electrolysispdf

[3] V Barmashenko and J Jorissen ldquoRecovery of chlorine fromdilute hydrochloric acid by electrolysis using a chlorine resistantanion exchange membranerdquo Journal of Applied Electrochem-istry vol 35 no 12 pp 1311ndash1319 2005

[4] ERCOWorldwide June 2015 httpwwwercoworldwidecomindexphpproductshydrochloric-acid

[5] Tetra Chemicals Europe June 2015 httpwwwtetrachemical-seuropecomResourcesLimestone-Hydrochloric Acid Processaqf

[6] P Rajeev A O Surendranathan and C S N Murthy ldquoCorro-sion mitigation of the oil well steels using organic inhibitorsmdashareviewrdquo Journal of Materials and Environmental Science vol 3no 5 pp 856ndash869 2012

[7] H Ando Y Uchida S Kohei C Knapp N Omoto and MKinoshita Trends and Views in the Development of Technologiesfor Chlorine Production from Hydrogen Chloride vol 2 Sumit-omo Kagaku R amp D Report Sumitomo Chemical Co 2010

[8] World Chlorine Council Sustainable Progress June 2015httpwwwworldchlorineorgwp-contentthemesbrickthe-mewppdfsreportpdf

[9] D Teschner R Farra L Yao et al ldquoAn integrated approachto Deacon chemistry on RuO

2-based catalystsrdquo Journal of

Catalysis vol 285 no 1 pp 273ndash284 2012

[10] T Vidakovic-Koch I G Martinez R Kuwertz U KunzT Turek and K Sundmacher ldquoElectrochemical membranereactors for sustainable chlorine recyclingrdquo Membranes vol 2no 3 pp 510ndash528 2012

[11] S W Benson and M W M Hisham ldquoEfficient method for thechemical production of chlorine and the separation of hydrogenchloride from complex mixturesrdquo US Patent 5154911 1992

[12] A D Benedictis and D B Luten Jr ldquoCatalysts for use in theproduction of Chlorinerdquo US patent 2448255 Dec 7 1943

[13] K Iwanaga K Seki T Hibi et alThe Development of ImprovedHydrogen Chloride Oxidation Process vol 1 Sumitomo KagakuR amp D Report Sumitomo Chemical 2004

[14] S Motupally D T Mah F J Freire and J W WeidnerldquoRecycling chlorine from hydrogen chloriderdquo Journal of theElectrochemical Society vol 7 pp 33ndash35 1998

[15] W F Engel and F Wattimena ldquoProcess for the production ofChlorinerdquo US patent 3210158 October 1965

[16] H Itoh Y Kono M Ajioka S Takenaka and M KataitaldquoProduction process of chlorinerdquo US Patent 4803065 1989

[17] J A Trainham N Del C G Law Jr et al ldquoElectrochemicalconversion of anhydrous hydrogen halide to halogen gas usinga cation-transporting membranerdquo US patent 5411641 May1995

[18] J Johnson and J Winnick ldquoElectrochemical membrane sep-aration of chlorine from gaseous hydrogen chloride wasterdquoSeparation and Purification Technology vol 15 no 3 pp 223ndash229 1999

[19] K Mazloomi N B Sulaiman and H Moayedi ldquoElectricalefficiency of electrolytic hydrogen productionrdquo InternationalJournal of Electrochemical Science vol 7 no 4 pp 3314ndash33262012

[20] S Koter and A Warszawski ldquoElectromembrane processesin environment protectionrdquo Polish Journal of EnvironmentalStudies vol 9 no 1 pp 45ndash56 2000

[21] Engineeringtoolbox Solubility of Chlorine GasmdashCl2mdashin

Water February 2015 httpwwwengineeringtoolboxcomgases-solubility-water-d 1148html

[22] College of Natural Sciences Chemistry Solubility of SelectedGases in Water February 2015 httpsiteschemcolostateedudiverdiall coursesCRC20reference20datasolubility20-of20gases20in20waterpdf

[23] E Zoulias E Varkaraki N Lymberopoulos C NChristodoulou and G N Karagiorgis ldquoA review on waterelectrolysisrdquo Tech Rep Centre for Renewable Energy SourcesPikermi Greece 2004 httpwwwcresgrkapepublicationspapersdimosieyseisydrogenA20REVIEW20ON20WA-TER20ELECTROLYSISpdf

[24] H-R M Jhong S Ma and P J A Kenis ldquoElectrochemicalconversion of CO

2to useful chemicals current status remain-

ing challenges and future opportunitiesrdquo Current Opinion inChemical Engineering vol 2 no 2 pp 191ndash199 2013

International Journal of

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Active and Passive Electronic Components

Control Scienceand Engineering

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Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

Acoustics and VibrationAdvances in



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Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks



Byproduct HCl

Calcium chloride Laboratory acid

Oil well

Muriatic acidSteel pickling

Domestic cleaning

36wt

10ndash12wt

15ndash18

wt

35

wt

5ndash35wt

20ndash30wt

Scheme 1 Uses of HCl recovered as byproduct [4ndash6]

demand for energy increases makes hydrogen important It isalso said that hydrogen being a clean fuel will be the sourceof energy in future So recovery of hydrogen and chlorine isbeing inevitably important industrially as time progresses

The market price of HCl can be under pressure becausethe expansion in demand for vinyl chloride monomers (mainrawmaterial isHCl) is smaller [7] Additionally since chloral-kali is the main route for producing chlorine industrially andthe expansion of the demand for chlorine (annual productionof Cl2globally is 58MMT [8] and has an expected demand

growth of 44 per year since 2010 [9]) is greater than thatof the demand for the caustic soda (NaOH) main product ofchloralkali process there is a danger that the demand balancebetween Cl

2and NaOHwill collapse [7] So it is important to

develop technologies for recovering chlorine and hydrogenfrom HCl and reutilizing it which can decrease the amountof excess HCl expected in market and also will balance thedemand of chlorine in market

Initially many processes are developed to recover chlo-rine like electrolysis (UHDE ODC) and catalytic oxidation(MT-Chlor) Although the recovery of chlorine from HClis being studied for more than 100 years the recovery ofboth hydrogen and chlorine is nevertheless studied less incomparison With this in background current study reportssimultaneous recovery of chlorine and hydrogen from indus-trial waste using batch electrolysis process An attempt hasbeen made to study the effect of various parameters whichaffect the conversion significantly The results and discussionare mainly focused on 2N (708wt) and 4N (1373 wt)because the industrial waste HCL generally is up to 20wt[10]

The recovery of hydrogen and chlorine if developed willhavemuch scope for application industrially One such exam-ple is phosgene mediated isocyanate production of TolueneDiisocyanate (TDI) the reactions shown below depict theprocess

CO + Cl2997888rarr COCl

2 (1)

CH3C6H3(NH2)2+ 2COCl

2

997888rarr CH3C6H3(NCO)

2+ 4HCl

(2)

For every 1 mole of TDI 4 moles of HCl is produced asbyproduct Approximately half of the Cl

2produced annually

is estimated to end up as HCl byproduct generated in the waydescribed above or as various other chlorides [7] So HCleither is a direct byproduct or is also produced when chlorineis removed in order to obtain chlorine-free products

Considering the concerns mentioned above with treatingindustrially waste dilute HCl it is a motivation to work onrecovery of both hydrogen and chlorine from waste diluteHCl from industries using electrolysis One of the mainadvantages of electrolysis is that it is a low temperature andpressure process and it can be monitored easily compared tooxidation processes

Different industrial recovery processes are explained inTable 1 Table 1 mainly summarizes two processes catalyticoxidation and ion exchange electrolysis The catalytic oxida-tion processes areDeaconKel-Chlor Shell-ChlorMT-Chlorand Sumitomo none of these processes recover hydrogen(it is lost as water) Out of these Kel-Chlor and Shell-Chlor are said to be commercialized but they are notoperational now only MT-Chlor and Sumitomo processesare commercially being used at present Even though catalyticoxidation processes are said to consume less energy the maindisadvantage is that they operate above 250∘C and productpurification involvesmultiple steps if feed conversions are less(even assuming 66 conversion the effluent has only 33Cl2) In contrast electrolysis is low temperature operation

and it is possible in few configurations (UHDE diaphragmand DuPont gas phase electrolysis) to recover both hydrogenand chlorine UHDE ODC is very much being licensedbecause of low energy consumption Table 2 summarizesresearch studies on recovering chlorine from HCl As can beseen the literature also reports similar electrolytic processeshowever studies on simultaneous recovery of both chlorineand hydrogen have not been many Moreover reportedstudies have been carried out for several hours of operationwhich do not seem to be economical Hence it is thoughtdesirable to work on the effect of different parameters affect-ing the electrolytic process However the other advantagesof recovering hydrogen and chlorine also include making theplant economics independent of both hydrogen and chlorine


Table1Indu

stria

lprocesses

ofchlorin

erecovery

Author

Process

Reactio

nMetho

dology

Con

clusio

nsRe

marks

Benson

andHish

am[11](19

92)

Deaconprocessd

evelop

edby

Henry

Deaconin

1868

[11]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Dire

ctoxidationarou

nd425to

475∘C[11]in

presence

ofcopp

ercatalyst

(ii)E

xothermicprocessh

asinterm

ediatereactio

nsresulting

inslu

ggish

reactio

nkinetic

s

(i)Lo

wer

yields

becauseo

flow

conversio

nandcatalystactiv

ity[12]

(ii)C

onstr

uctio

nisexpensive

duetohigh

lycorrosive[11]

interm

ediates

(i)Sing

lepassconversio

nsarou

nd60to

80

(ii)C

atalystactivity

decreasesa

bove

402∘C

becauseo

fvolatilizatio

n[9]

(iii)Never

been

putto

commercialuse[1213]

And

oetal[7]

(2010)

Kel-C

hlor

byKe

llogg

inthe1960s

[14]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Oxidatio

nusing

nitro

genoxides

asthe

catalystandsulphu

ricacid

ascirculatingmedium

[7]

(i)Needs

expensivep

lant

desig

nandsafetyfeatures

becauseo

fmanyinterm

ediatereactio

nste

ps[711]m

akingiton

lypo

ssiblefor

large-scalep

lants

(i)Needs

extensive

downstre

amprocessin

gto

getp

urec

hlorine

(ii)D

uPon

tstarted

20000

0ton

yearp

lant

in1974but

itisno

toperatin

gatpresent[7]

Engeland

Wattim

ena[

15](1965)

Shell-C

hlor

byShell

patented

in1965

[15]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Oxidatio

nin

fluidized

bedprocessat300

to425∘C

(ii)C

atalystisc

ompo

sedof

copp

erchloriderare

earth

materials

andothersat

determ

ined

ratio

[15]


itybecause

oflowvolatilization

(ii)C

orrosio

nisalso

less[15]

(i)Con

versionof

80can

beachieved

[15]

(ii)S

hellop

erated

afacility

of30000

tyrinthe1970s

[13]but

operationwas

eventuallyshut

down

ThyssenK

rupp

[2]

UHDEdiaphragm

process

developedby

Bayer

MaterialScience

ampUhd

enora

Ano

de

2Clminusrarr

2Cl 2+2eminus

Cathod

e2H++

2eminusrarr

H2

(i)Aq

ueou

selectrolysis

processu

singPV

CPV

DF

diaphragm

at65

to70∘C

[2]

(ii)G

raph

iteelectro

desa

reusedW

ater

transfe

r(osm

aticdrag)isp

resent

(i)Gas

purityislim

itedbecause

thed

iaph

ragm

cann

otim

pede

gasd

iffusioncompletely

[3]

(ii)M

inim

umHCl

concentrations

shou

ldbe

maintainedto

avoidoxygen

evolution[3]

(i)Th

econ

versionis25

(23to

17wt

)(ii)P

ower

consum

ptionis

1670

kWhtminus1Cl2at5k

Amminus2

[2]

(iii)In

Germanyin

1995

20of

theH

Clprod

uced

was

recycle

dthisway

[3]

Itohetal[16](1989)

MT-Ch

lorb

yMitsui

Toatsu

patented

in1989

[16]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Oxidatio

nin

fluidized

bedprocessu

singCr2O3sdot

SiO2catalyst[7]in

presence

ofpu

reoxygen

[16]


(i)UnlikeD

eaconhere

catalyst

operates

with

outm

eltingso

the

stabilityof

thec

atalystisg

reatly

improved

[7]

(i)Con

versions

upto

80

canbe

achieved

[16]

(ii)O

mutas

ince

1988

has

60000

tycapacityplant

operatingsuccessfu

lly[7]

Trainh

ametal[17](1995)

DuP

ontgas

phase

electrolysis

byDuP

ontd

eNem

ourspatented

in1995

[17]

Ano

de2HCl

(g)rarr

Cl2(g)+

2H+(aq)

+2eminus

Cathod

e2H+(aq)

+2eminusrarr

H2(g)

(i)SimilartoCE

Mele

ctrolysis

processb

utoccursin

gasp

hase

throug

hgasd

iffusiontype

mem

branes

(ii)Th

eelectrolyseris

operated

at450ndash

550k

Paand70ndash9

0∘C

(i)NoHCL

absorptio

nste

p(ii)S

impled

ownstre

amprocess

issufficientfor

purifi

catio


s[14]

(iii)Water

transport(osmatic

drag)isp

resent

(i)HCl

conversio

nratio

upto

85[7]can

beachieved

becauseo

fhighdiffu

sion

coeffi

cients(gas

phase)[14

](ii)P

ower

consum

ptionat

5kAmminus2isroug

hly

1120

kWhtCl 2[14

]


Table1Con

tinued

Author

Process

Reactio

nMetho

dology

Con

clusio

nsRe

marks

Iwanagae

tal[13]

(200

4)

Sumito

moprocessb

ySumito

moCh

emicalCo

Ltddevelopedin

2000

[13]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Oxidatio

nprocessin

fixed

bedreactoru

sing


Canbe

operated

aslowas

250∘C

(ii)Th

isprocessh

ashigh

erconversio

nsbecauseo

ffix

edbedreactor

(i)Th

iscatalysthash

igher

activ


than

theo

nesd

iscussedabove

[13]

(ii)S

ince

2003

aplant

having

prod

uctio

ncapacityof

10000

0ty

isop

eratingsm

oothly

(i)Con

versions

upto

95

arep

ossib

le[13]

(ii)P

ower

consum

ptionis

165k

Whtminus1Cl2[13]

which

isvery

lessincomparis

onto

Bayer-DENoraP

rocess

butn

ocomparis

onsfor

capitalcostsarer

eported

ThyssenK

rupp

[2]

UHDEODCprocess

developedby

Bayer

MaterialScience

ampUhd

enora

Ano

de4HCl

(aq)rarr

4H++4eminus

+2C

l 2Ca

thod

e4H++

4eminus+O2rarr

2H2O

(i)SimilartoCE

Melectro

lysis

processbu

thydrogen

generatio

nis

supp

ressed

bywater

form

ationresulting

in30

saving

sinele

ctric

consum

ptionandvoltage

lessthan

1V[2]

(i)Water

transportisp

resent

from

anod

etocathod

e(ii)M


gthistechno

logyfor

exam

ple

Bayerstarted

operatinga

commercialplanto

f215000

tyr

[7]

(i)Th

epow

erconsum

ption

is1070

kWhtminus1Cl2at


diaphragm

processbu

tthe

capitalcostsforthe

same

aren

otrepo

rted

















2















Table 2 Continued















2(aq) (3)








Voltage regulator



31

2

1

2

H2

Clminus

H2O

2eminus 2eminus

Cl2

2H+rarrH2

2Clminus rarrCl2



Conversion

= 100

lowast (1 minus (


))

(5)





0

04

08

12

16

2

24

28

32

36

4

0 10 20 30 40 50 60 70 80 90 100

Tota

l cha

rge (

ampe

re h

ours

)


40N20N



Chlorine recovery

=


lowast 100

(7)




Chlo

rine s

olub

ility

(gm

kg

wat

er)

10

9

8

7

6

5

4

3

2

1

0

0 20 40 60 80 100


0

10

20

30

40

50

60

70

80

90

100

110

120

130

0 1 2 3 4 5 6 7 8 9 10

Chlo

rine r

ecov

ery

perc

ent (

mdash)





0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Hyd

roge

n re

cove

ry p

erce

nt (mdash

)




Hydrogen Recovery

=


lowast 100

(8)







Minimum voltage(V)

4 14 172 14 234 72 152 72 16




2+OHminus (9)



0

1

2

3

4

5

0 10 20 30 40 50 60 70 80 90 100

EOD

(mL)


4N


0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Con

vers

ion

perc

ent (

mdash)





0

03

06

09

12

15

18

21

24

27

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20To

tal c

harg

e (am

pere

hou

rs)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





0

04

08

12

16

2

24

28

32

36

4

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20

Tota

l cha

rge (

ampe

re h

ours

)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





(10)









0

05

1

15

2

25

3

35

4

45

0 1 2 3 4

Cath

olyt

e con

cent

ratio

n (n

orm

ality

)


40N20N





119876

(11)

0

05

1

15

2

25

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)





0

05

1

15

2

25

3

35

4

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)



4 Conclusion


0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18

Curr

ent e

ffici

ency

per

cent

(mdash)

Voltage (volts)

4N2N















Competing Interests


References
































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Table1Indu

stria

lprocesses

ofchlorin

erecovery

Author

Process

Reactio

nMetho

dology

Con

clusio

nsRe

marks

Benson

andHish

am[11](19

92)

Deaconprocessd

evelop

edby

Henry

Deaconin

1868

[11]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Dire

ctoxidationarou

nd425to

475∘C[11]in

presence

ofcopp

ercatalyst

(ii)E

xothermicprocessh

asinterm

ediatereactio

nsresulting

inslu

ggish

reactio

nkinetic

s

(i)Lo

wer

yields

becauseo

flow

conversio

nandcatalystactiv

ity[12]

(ii)C

onstr

uctio

nisexpensive

duetohigh

lycorrosive[11]

interm

ediates

(i)Sing

lepassconversio

nsarou

nd60to

80

(ii)C

atalystactivity

decreasesa

bove

402∘C

becauseo

fvolatilizatio

n[9]

(iii)Never

been

putto

commercialuse[1213]

And

oetal[7]

(2010)

Kel-C

hlor

byKe

llogg

inthe1960s

[14]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Oxidatio

nusing

nitro

genoxides

asthe

catalystandsulphu

ricacid

ascirculatingmedium

[7]

(i)Needs

expensivep

lant

desig

nandsafetyfeatures

becauseo

fmanyinterm

ediatereactio

nste

ps[711]m

akingiton

lypo

ssiblefor

large-scalep

lants

(i)Needs

extensive

downstre

amprocessin

gto

getp

urec

hlorine

(ii)D

uPon

tstarted

20000

0ton

yearp

lant

in1974but

itisno

toperatin

gatpresent[7]

Engeland

Wattim

ena[

15](1965)

Shell-C

hlor

byShell

patented

in1965

[15]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Oxidatio

nin

fluidized

bedprocessat300

to425∘C

(ii)C

atalystisc

ompo

sedof

copp

erchloriderare

earth

materials

andothersat

determ

ined

ratio

[15]


itybecause

oflowvolatilization

(ii)C

orrosio

nisalso

less[15]

(i)Con

versionof

80can

beachieved

[15]

(ii)S

hellop

erated

afacility

of30000

tyrinthe1970s

[13]but

operationwas

eventuallyshut

down

ThyssenK

rupp

[2]

UHDEdiaphragm

process

developedby

Bayer

MaterialScience

ampUhd

enora

Ano

de

2Clminusrarr

2Cl 2+2eminus

Cathod

e2H++

2eminusrarr

H2

(i)Aq

ueou

selectrolysis

processu

singPV

CPV

DF

diaphragm

at65

to70∘C

[2]

(ii)G

raph

iteelectro

desa

reusedW

ater

transfe

r(osm

aticdrag)isp

resent

(i)Gas

purityislim

itedbecause

thed

iaph

ragm

cann

otim

pede

gasd

iffusioncompletely

[3]

(ii)M

inim

umHCl

concentrations

shou

ldbe

maintainedto

avoidoxygen

evolution[3]

(i)Th

econ

versionis25

(23to

17wt

)(ii)P

ower

consum

ptionis

1670

kWhtminus1Cl2at5k

Amminus2

[2]

(iii)In

Germanyin

1995

20of

theH

Clprod

uced

was

recycle

dthisway

[3]

Itohetal[16](1989)

MT-Ch

lorb

yMitsui

Toatsu

patented

in1989

[16]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Oxidatio

nin

fluidized

bedprocessu

singCr2O3sdot

SiO2catalyst[7]in

presence

ofpu

reoxygen

[16]


(i)UnlikeD

eaconhere

catalyst

operates

with

outm

eltingso

the

stabilityof

thec

atalystisg

reatly

improved

[7]

(i)Con

versions

upto

80

canbe

achieved

[16]

(ii)O

mutas

ince

1988

has

60000

tycapacityplant

operatingsuccessfu

lly[7]

Trainh

ametal[17](1995)

DuP

ontgas

phase

electrolysis

byDuP

ontd

eNem

ourspatented

in1995

[17]

Ano

de2HCl

(g)rarr

Cl2(g)+

2H+(aq)

+2eminus

Cathod

e2H+(aq)

+2eminusrarr

H2(g)

(i)SimilartoCE

Mele

ctrolysis

processb

utoccursin

gasp

hase

throug

hgasd

iffusiontype

mem

branes

(ii)Th

eelectrolyseris

operated

at450ndash

550k

Paand70ndash9

0∘C

(i)NoHCL

absorptio

nste

p(ii)S

impled

ownstre

amprocess

issufficientfor

purifi

catio


s[14]

(iii)Water

transport(osmatic

drag)isp

resent

(i)HCl

conversio

nratio

upto

85[7]can

beachieved

becauseo

fhighdiffu

sion

coeffi

cients(gas

phase)[14

](ii)P

ower

consum

ptionat

5kAmminus2isroug

hly

1120

kWhtCl 2[14

]


Table1Con

tinued

Author

Process

Reactio

nMetho

dology

Con

clusio

nsRe

marks

Iwanagae

tal[13]

(200

4)

Sumito

moprocessb

ySumito

moCh

emicalCo

Ltddevelopedin

2000

[13]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Oxidatio

nprocessin

fixed

bedreactoru

sing


Canbe

operated

aslowas

250∘C

(ii)Th

isprocessh

ashigh

erconversio

nsbecauseo

ffix

edbedreactor

(i)Th

iscatalysthash

igher

activ


than

theo

nesd

iscussedabove

[13]

(ii)S

ince

2003

aplant

having

prod

uctio

ncapacityof

10000

0ty

isop

eratingsm

oothly

(i)Con

versions

upto

95

arep

ossib

le[13]

(ii)P

ower

consum

ptionis

165k

Whtminus1Cl2[13]

which

isvery

lessincomparis

onto

Bayer-DENoraP

rocess

butn

ocomparis

onsfor

capitalcostsarer

eported

ThyssenK

rupp

[2]

UHDEODCprocess

developedby

Bayer

MaterialScience

ampUhd

enora

Ano

de4HCl

(aq)rarr

4H++4eminus

+2C

l 2Ca

thod

e4H++

4eminus+O2rarr

2H2O

(i)SimilartoCE

Melectro

lysis

processbu

thydrogen

generatio

nis

supp

ressed

bywater

form

ationresulting

in30

saving

sinele

ctric

consum

ptionandvoltage

lessthan

1V[2]

(i)Water

transportisp

resent

from

anod

etocathod

e(ii)M


gthistechno

logyfor

exam

ple

Bayerstarted

operatinga

commercialplanto

f215000

tyr

[7]

(i)Th

epow

erconsum

ption

is1070

kWhtminus1Cl2at


diaphragm

processbu

tthe

capitalcostsforthe

same

aren

otrepo

rted

















2















Table 2 Continued















2(aq) (3)








Voltage regulator



31

2

1

2

H2

Clminus

H2O

2eminus 2eminus

Cl2

2H+rarrH2

2Clminus rarrCl2



Conversion

= 100

lowast (1 minus (


))

(5)





0

04

08

12

16

2

24

28

32

36

4

0 10 20 30 40 50 60 70 80 90 100

Tota

l cha

rge (

ampe

re h

ours

)


40N20N



Chlorine recovery

=


lowast 100

(7)




Chlo

rine s

olub

ility

(gm

kg

wat

er)

10

9

8

7

6

5

4

3

2

1

0

0 20 40 60 80 100


0

10

20

30

40

50

60

70

80

90

100

110

120

130

0 1 2 3 4 5 6 7 8 9 10

Chlo

rine r

ecov

ery

perc

ent (

mdash)





0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Hyd

roge

n re

cove

ry p

erce

nt (mdash

)




Hydrogen Recovery

=


lowast 100

(8)







Minimum voltage(V)

4 14 172 14 234 72 152 72 16




2+OHminus (9)



0

1

2

3

4

5

0 10 20 30 40 50 60 70 80 90 100

EOD

(mL)


4N


0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Con

vers

ion

perc

ent (

mdash)





0

03

06

09

12

15

18

21

24

27

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20To

tal c

harg

e (am

pere

hou

rs)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





0

04

08

12

16

2

24

28

32

36

4

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20

Tota

l cha

rge (

ampe

re h

ours

)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





(10)









0

05

1

15

2

25

3

35

4

45

0 1 2 3 4

Cath

olyt

e con

cent

ratio

n (n

orm

ality

)


40N20N





119876

(11)

0

05

1

15

2

25

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)





0

05

1

15

2

25

3

35

4

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)



4 Conclusion


0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18

Curr

ent e

ffici

ency

per

cent

(mdash)

Voltage (volts)

4N2N















Competing Interests


References
































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Table1Con

tinued

Author

Process

Reactio

nMetho

dology

Con

clusio

nsRe

marks

Iwanagae

tal[13]

(200

4)

Sumito

moprocessb

ySumito

moCh

emicalCo

Ltddevelopedin

2000

[13]

4HCl

+O2rarr

2Cl 2

+2H2O

(i)Oxidatio

nprocessin

fixed

bedreactoru

sing


Canbe

operated

aslowas

250∘C

(ii)Th

isprocessh

ashigh

erconversio

nsbecauseo

ffix

edbedreactor

(i)Th

iscatalysthash

igher

activ


than

theo

nesd

iscussedabove

[13]

(ii)S

ince

2003

aplant

having

prod

uctio

ncapacityof

10000

0ty

isop

eratingsm

oothly

(i)Con

versions

upto

95

arep

ossib

le[13]

(ii)P

ower

consum

ptionis

165k

Whtminus1Cl2[13]

which

isvery

lessincomparis

onto

Bayer-DENoraP

rocess

butn

ocomparis

onsfor

capitalcostsarer

eported

ThyssenK

rupp

[2]

UHDEODCprocess

developedby

Bayer

MaterialScience

ampUhd

enora

Ano

de4HCl

(aq)rarr

4H++4eminus

+2C

l 2Ca

thod

e4H++

4eminus+O2rarr

2H2O

(i)SimilartoCE

Melectro

lysis

processbu

thydrogen

generatio

nis

supp

ressed

bywater

form

ationresulting

in30

saving

sinele

ctric

consum

ptionandvoltage

lessthan

1V[2]

(i)Water

transportisp

resent

from

anod

etocathod

e(ii)M


gthistechno

logyfor

exam

ple

Bayerstarted

operatinga

commercialplanto

f215000

tyr

[7]

(i)Th

epow

erconsum

ption

is1070

kWhtminus1Cl2at


diaphragm

processbu

tthe

capitalcostsforthe

same

aren

otrepo

rted

















2















Table 2 Continued















2(aq) (3)








Voltage regulator



31

2

1

2

H2

Clminus

H2O

2eminus 2eminus

Cl2

2H+rarrH2

2Clminus rarrCl2



Conversion

= 100

lowast (1 minus (


))

(5)





0

04

08

12

16

2

24

28

32

36

4

0 10 20 30 40 50 60 70 80 90 100

Tota

l cha

rge (

ampe

re h

ours

)


40N20N



Chlorine recovery

=


lowast 100

(7)




Chlo

rine s

olub

ility

(gm

kg

wat

er)

10

9

8

7

6

5

4

3

2

1

0

0 20 40 60 80 100


0

10

20

30

40

50

60

70

80

90

100

110

120

130

0 1 2 3 4 5 6 7 8 9 10

Chlo

rine r

ecov

ery

perc

ent (

mdash)





0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Hyd

roge

n re

cove

ry p

erce

nt (mdash

)




Hydrogen Recovery

=


lowast 100

(8)







Minimum voltage(V)

4 14 172 14 234 72 152 72 16




2+OHminus (9)



0

1

2

3

4

5

0 10 20 30 40 50 60 70 80 90 100

EOD

(mL)


4N


0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Con

vers

ion

perc

ent (

mdash)





0

03

06

09

12

15

18

21

24

27

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20To

tal c

harg

e (am

pere

hou

rs)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





0

04

08

12

16

2

24

28

32

36

4

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20

Tota

l cha

rge (

ampe

re h

ours

)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





(10)









0

05

1

15

2

25

3

35

4

45

0 1 2 3 4

Cath

olyt

e con

cent

ratio

n (n

orm

ality

)


40N20N





119876

(11)

0

05

1

15

2

25

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)





0

05

1

15

2

25

3

35

4

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)



4 Conclusion


0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18

Curr

ent e

ffici

ency

per

cent

(mdash)

Voltage (volts)

4N2N















Competing Interests


References
































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation

























2















Table 2 Continued















2(aq) (3)








Voltage regulator



31

2

1

2

H2

Clminus

H2O

2eminus 2eminus

Cl2

2H+rarrH2

2Clminus rarrCl2



Conversion

= 100

lowast (1 minus (


))

(5)





0

04

08

12

16

2

24

28

32

36

4

0 10 20 30 40 50 60 70 80 90 100

Tota

l cha

rge (

ampe

re h

ours

)


40N20N



Chlorine recovery

=


lowast 100

(7)




Chlo

rine s

olub

ility

(gm

kg

wat

er)

10

9

8

7

6

5

4

3

2

1

0

0 20 40 60 80 100


0

10

20

30

40

50

60

70

80

90

100

110

120

130

0 1 2 3 4 5 6 7 8 9 10

Chlo

rine r

ecov

ery

perc

ent (

mdash)





0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Hyd

roge

n re

cove

ry p

erce

nt (mdash

)




Hydrogen Recovery

=


lowast 100

(8)







Minimum voltage(V)

4 14 172 14 234 72 152 72 16




2+OHminus (9)



0

1

2

3

4

5

0 10 20 30 40 50 60 70 80 90 100

EOD

(mL)


4N


0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Con

vers

ion

perc

ent (

mdash)





0

03

06

09

12

15

18

21

24

27

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20To

tal c

harg

e (am

pere

hou

rs)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





0

04

08

12

16

2

24

28

32

36

4

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20

Tota

l cha

rge (

ampe

re h

ours

)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





(10)









0

05

1

15

2

25

3

35

4

45

0 1 2 3 4

Cath

olyt

e con

cent

ratio

n (n

orm

ality

)


40N20N





119876

(11)

0

05

1

15

2

25

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)





0

05

1

15

2

25

3

35

4

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)



4 Conclusion


0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18

Curr

ent e

ffici

ency

per

cent

(mdash)

Voltage (volts)

4N2N















Competing Interests


References
































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Table 2 Continued















2(aq) (3)








Voltage regulator



31

2

1

2

H2

Clminus

H2O

2eminus 2eminus

Cl2

2H+rarrH2

2Clminus rarrCl2



Conversion

= 100

lowast (1 minus (


))

(5)





0

04

08

12

16

2

24

28

32

36

4

0 10 20 30 40 50 60 70 80 90 100

Tota

l cha

rge (

ampe

re h

ours

)


40N20N



Chlorine recovery

=


lowast 100

(7)




Chlo

rine s

olub

ility

(gm

kg

wat

er)

10

9

8

7

6

5

4

3

2

1

0

0 20 40 60 80 100


0

10

20

30

40

50

60

70

80

90

100

110

120

130

0 1 2 3 4 5 6 7 8 9 10

Chlo

rine r

ecov

ery

perc

ent (

mdash)





0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Hyd

roge

n re

cove

ry p

erce

nt (mdash

)




Hydrogen Recovery

=


lowast 100

(8)







Minimum voltage(V)

4 14 172 14 234 72 152 72 16




2+OHminus (9)



0

1

2

3

4

5

0 10 20 30 40 50 60 70 80 90 100

EOD

(mL)


4N


0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Con

vers

ion

perc

ent (

mdash)





0

03

06

09

12

15

18

21

24

27

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20To

tal c

harg

e (am

pere

hou

rs)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





0

04

08

12

16

2

24

28

32

36

4

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20

Tota

l cha

rge (

ampe

re h

ours

)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





(10)









0

05

1

15

2

25

3

35

4

45

0 1 2 3 4

Cath

olyt

e con

cent

ratio

n (n

orm

ality

)


40N20N





119876

(11)

0

05

1

15

2

25

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)





0

05

1

15

2

25

3

35

4

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)



4 Conclusion


0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18

Curr

ent e

ffici

ency

per

cent

(mdash)

Voltage (volts)

4N2N















Competing Interests


References
































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Voltage regulator



31

2

1

2

H2

Clminus

H2O

2eminus 2eminus

Cl2

2H+rarrH2

2Clminus rarrCl2



Conversion

= 100

lowast (1 minus (


))

(5)





0

04

08

12

16

2

24

28

32

36

4

0 10 20 30 40 50 60 70 80 90 100

Tota

l cha

rge (

ampe

re h

ours

)


40N20N



Chlorine recovery

=


lowast 100

(7)




Chlo

rine s

olub

ility

(gm

kg

wat

er)

10

9

8

7

6

5

4

3

2

1

0

0 20 40 60 80 100


0

10

20

30

40

50

60

70

80

90

100

110

120

130

0 1 2 3 4 5 6 7 8 9 10

Chlo

rine r

ecov

ery

perc

ent (

mdash)





0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Hyd

roge

n re

cove

ry p

erce

nt (mdash

)




Hydrogen Recovery

=


lowast 100

(8)







Minimum voltage(V)

4 14 172 14 234 72 152 72 16




2+OHminus (9)



0

1

2

3

4

5

0 10 20 30 40 50 60 70 80 90 100

EOD

(mL)


4N


0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Con

vers

ion

perc

ent (

mdash)





0

03

06

09

12

15

18

21

24

27

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20To

tal c

harg

e (am

pere

hou

rs)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





0

04

08

12

16

2

24

28

32

36

4

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20

Tota

l cha

rge (

ampe

re h

ours

)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





(10)









0

05

1

15

2

25

3

35

4

45

0 1 2 3 4

Cath

olyt

e con

cent

ratio

n (n

orm

ality

)


40N20N





119876

(11)

0

05

1

15

2

25

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)





0

05

1

15

2

25

3

35

4

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)



4 Conclusion


0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18

Curr

ent e

ffici

ency

per

cent

(mdash)

Voltage (volts)

4N2N















Competing Interests


References
































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











Chlo

rine s

olub

ility

(gm

kg

wat

er)

10

9

8

7

6

5

4

3

2

1

0

0 20 40 60 80 100


0

10

20

30

40

50

60

70

80

90

100

110

120

130

0 1 2 3 4 5 6 7 8 9 10

Chlo

rine r

ecov

ery

perc

ent (

mdash)





0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Hyd

roge

n re

cove

ry p

erce

nt (mdash

)




Hydrogen Recovery

=


lowast 100

(8)







Minimum voltage(V)

4 14 172 14 234 72 152 72 16




2+OHminus (9)



0

1

2

3

4

5

0 10 20 30 40 50 60 70 80 90 100

EOD

(mL)


4N


0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Con

vers

ion

perc

ent (

mdash)





0

03

06

09

12

15

18

21

24

27

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20To

tal c

harg

e (am

pere

hou

rs)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





0

04

08

12

16

2

24

28

32

36

4

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20

Tota

l cha

rge (

ampe

re h

ours

)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





(10)









0

05

1

15

2

25

3

35

4

45

0 1 2 3 4

Cath

olyt

e con

cent

ratio

n (n

orm

ality

)


40N20N





119876

(11)

0

05

1

15

2

25

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)





0

05

1

15

2

25

3

35

4

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)



4 Conclusion


0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18

Curr

ent e

ffici

ency

per

cent

(mdash)

Voltage (volts)

4N2N















Competing Interests


References
































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation













Minimum voltage(V)

4 14 172 14 234 72 152 72 16




2+OHminus (9)



0

1

2

3

4

5

0 10 20 30 40 50 60 70 80 90 100

EOD

(mL)


4N


0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10

Con

vers

ion

perc

ent (

mdash)





0

03

06

09

12

15

18

21

24

27

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20To

tal c

harg

e (am

pere

hou

rs)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





0

04

08

12

16

2

24

28

32

36

4

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20

Tota

l cha

rge (

ampe

re h

ours

)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





(10)









0

05

1

15

2

25

3

35

4

45

0 1 2 3 4

Cath

olyt

e con

cent

ratio

n (n

orm

ality

)


40N20N





119876

(11)

0

05

1

15

2

25

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)





0

05

1

15

2

25

3

35

4

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)



4 Conclusion


0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18

Curr

ent e

ffici

ency

per

cent

(mdash)

Voltage (volts)

4N2N















Competing Interests


References
































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










0

03

06

09

12

15

18

21

24

27

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20To

tal c

harg

e (am

pere

hou

rs)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





0

04

08

12

16

2

24

28

32

36

4

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20

Tota

l cha

rge (

ampe

re h

ours

)

Voltage (volts)


Con

vers

ion

perc

ent (

mdash)





(10)









0

05

1

15

2

25

3

35

4

45

0 1 2 3 4

Cath

olyt

e con

cent

ratio

n (n

orm

ality

)


40N20N





119876

(11)

0

05

1

15

2

25

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)





0

05

1

15

2

25

3

35

4

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)



4 Conclusion


0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18

Curr

ent e

ffici

ency

per

cent

(mdash)

Voltage (volts)

4N2N















Competing Interests


References
































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation
















0

05

1

15

2

25

3

35

4

45

0 1 2 3 4

Cath

olyt

e con

cent

ratio

n (n

orm

ality

)


40N20N





119876

(11)

0

05

1

15

2

25

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)





0

05

1

15

2

25

3

35

4

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)



4 Conclusion


0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18

Curr

ent e

ffici

ency

per

cent

(mdash)

Voltage (volts)

4N2N















Competing Interests


References
































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










0

05

1

15

2

25

3

35

4

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180ED (mm)

Tota

l cha

rge (

ampe

re h

ours

)


Con

vers

ion

perc

ent (

mdash)



4 Conclusion


0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18

Curr

ent e

ffici

ency

per

cent

(mdash)

Voltage (volts)

4N2N















Competing Interests


References
































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation















Competing Interests


References
































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









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Research Article Simultaneous Recovery of Hydrogen and Chlorine...

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