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The_113the,The

    The

Apr.2008,Volume2,No.4(SerialNo.5)JournalofChemistryandChemicalEngineering,ISS

    N1934.7375,USA

    ;Thepreparationofhighperformancecarbonelectrode ;inelectrochemicaloxygengenerator

    ;LUOZhiyong,CHENMaobin,ZHANGShengtao

    ;fCollegeofChemist~&ChemicalEngineering,ChongqingUniversi~,Chongqing4

    00044,China)

    ;Abstract:Theelectrochemicaloxygengeneratorhasbeen ;popularizedforitsvirtues,suchashighoxygenconcentration ;output,electricitysaving,easyoperationandmaintenance.The ;keypartofelectrochemicaloxygengeneratoriscarbonelectrode ;usedasthecathode.Thepreparationofhighperformancecarbon ;electrodewasintroducedinthispaper.Thepropertiesofcarbon ;electrodewastested.Theelectrochemicaloxygengenerator ;usingcarbonelectrodeasthecathodewasprepared.Theoxygen ;concentrationandflowofthismachineishigherthanthatof ;othersiflChina.

    ;Keywords:theelectrochemicaloxygengenerator;carbon ;electrode;preparation

    ;1.Introduction

    ;Theoxygenisoftenofferedinthelargehospital

    ;byoxygengenerator.Basedontheprincipleof

    ;pressureswingadsorption,themachinecanmake

    ;oxygenbymolecularsieve.Butthismachineisn’t

    ;popularizedforlowoxygenconcentrationoutput,high ;costanddifficultmaintenance.Theoxygenisoften ;offeredinthesmallhospitalandfamilybyoxygen

    ;bottle/bag.Butthecapacityofstorageoxygenin

    ;oxygenbottle/bagislimited.Itcanonlymeetfewer ;peopleinshorttime,notinlongtime.Especiallywe ;musttakemanyoxygenbottles/bagswhenwetourin

    ;tableland.Anotheroxygengeneratingwayischemica1.

    ;Itisn’tpopularizedforhighcostandshorttimeof

    ;oxygenoutput[1,21.

    ;Acknowledgements:The

    ;UndergraduateInnovation

    ;ChongqingUniversity(No.

    ;authorsthanktheNational

    ;Experiments’Foundationof

;CQUCX?-G?200712)forfinancial

    ;support.

    ;Correspondingauthor:LUOZhiyong(1974-),male,Ph.D.

    ;candidate;researchfields:physicalchemistryand ;electrochemistry.Email:luozy@cqu.edu.ca.

    ;Inordertoavoidthesedisadvantages,the

    ;electrochemicaloxygengeneratorhasbeendeveloped ;inrecentyears[3,51.Comparedtogeneralelectrolyzing ;water,hydrogenisn’tproducedintheelectrochemical

    ;oxygengenerator.Sooxygenconcentrationofthis ;machineisveryhighandreachthenationalstandardof ;medicaloxygen(>99.5%).Atthesametimethe ;explosionthatiscausedbythemixtureofhydrogen ;andoxygencanbeeliminated.Soitisverysafe.There ;aremanyothervirtuesinthismachine,suchassmall ;bulk,lightweight,lowcost,nocontamination,little ;noise,electricitysaving,andeasyoperation[6.7]. ;Inordertoguaranteethereactionwithout

    ;hydrogeninthismachine,carbonelectrodeusedasthe ;cathodeinelectrochemicaloxygengeneratorwas ;preparedbytheauthors.Theelectrodewascomposed ;ofwaterproofbreathablemembrane,electricnetand ;catalyticmembrane.Itwasmadefromspecial ;composite.Oxygeninairenteredintointerfaceof ;catalyticmembranethroughwaterproofbreathable ;membraneiflthesurfaceofcarbonelectrode.Thenthe ;interfaceofgas,liquidandsolidwasformed.Sothe ;oxygenwasreducedeasily.Thealkalinesolutionwas ;usedastheelectrolytem.Theelectrodereactionin ;electrochemicaloxygengeneratorisdescribedinthe ;following.

    ;Anodicreaction:

    ;4OH02T+2H2O+4e

    ;Cathodicreaction:

    ;02(inair)+2H20+4e—}40H’

    ;Reaction(1)plusreaction(2)isoverall

    ;Overallreaction:

    ;(1)

    ;(2)

    ;reaction.

    ;57

    ;Thepreparationofhighperformancecarbonelectrodeinelectrochemicaloxygengenerato

    r

    ;O2(inair)O2(3)

    ;Becausecarbonelectrodewassubstitutedfor ;hydrogenevolutionelectrode,oxygenwasn’tproduced

    ;inthecathode.Thusitcanbeseenthatcarbonelectrode ;isakeypartofelectrochemicaloxygengenerator.It ;hasaneffectoncurrentdensity,oxygenf/owand ;concentration,andoperativelifetimeof

    ;electrochemicaloxygengenerator.Sothepreparation ;ofcarbonelectrodeisveryimportant.Thispaper ;introducedhowtopreparecarbonelectrodeandtestits ;properties.

    ;2.Theequipmentsofexperiment

    ;RG2000-50electronicuniversalmaterialtesting ;machinemadeinShenzhen;QJ36DCsinglearmand

    ;doublearmbridgesmadeinShanghai;Purity

    ;equipment;grindingmachine;ovenandmuffle. ;3.Thepreparationofcarbonelectrode

    ;carbonelectrodeusedasthecathodein

    ;electrochemicaloxygengeneratorisakindofair ;electrode.Duetocarbonelectrodeusedasthecathode, ;pureoxygenismadefromoxygeninairby

    ;electrochemicaloxygengenerator.Sothepropertiesof ;carbonelectrodedecidethepurityofoxygenmadeby ;oxygengenerator.Thereforethepreparationofhigh ;performancecarbonelectrodeisveryimportant. ;Waterproofbreathablemembrane,electricnet ;andcatalyticmembranewereputinturnandpressed. ;Thencarbonelectrodewasprepared.Bytheactivated ;disposalinsometemperature,highperformance ;carbonelectrodecouldbeprepared.TheElectricnetin ;carbonelectrodewasmadefromcopper.Inorderto ;improveconductivity,Electricnetwasknittedby ;copperandthencoatedwithsilver.Thepreparationof ;waterproofbreathablemembraneandcatalytic ;membraneincarbonelectrodearedescribed ;respectivelyinthefollowing.

    ;3.1Thepreparationofwaterproofbreathable ;membrane

    ;Oxygeninairisusedasanactivatingagentin ;electrochemicaloxygengenerator.Oxygencontinues ;tobereactedintheinterfaceofthreephasesthrough

    ;waterproofbreathablemembrane.Sohowtocontrol ;gasdiffusionisveryimportant….Thequantityofgas

    ;diffusionisrelatedwiththecomponentandproductive ;conditionofwaterproofbreathablemembrane.The

    ;preparationofwaterproofbreathablemembranewhich ;uses60%PTFE,ethanol,andacetyleneblackasraw ;materialsisshowninFig.1.

    ;DistilledwaterAcetyleneblack

    ;l

    ;-?Equablemixture__’Dehydration1DryingExtractinginacetone

    ;.I

    Dippinginisopropanol+_-Dn;WaterproofbreathablemembraneGrindingin70-80~C~---g

    ;Fig.1Thepreparationofwaterproofbreathablemembrane ;Extractioninacetoneandgrindingin7080~Care

    ;thekeyfactorsinthepreparation.Thenetstructureof ;Polytetrafluoroethyleneisformedatthemomentof ;grinding.Thisstructureiswaterproof,stickyandcan ;58

    ;prolongoperativelifetimeofwaterproofbreathable ;membrane.

    ;3.2Thepreparationofcatalyticmembrane

    ;Ifcatalyticmembraneisthinandnearto

    ;electrolyte,ohmpolarizationandconcentration ;Thepep.d.dti9ighperformancecarbonelectrodeinelectrochemicaloxygengenerator

    ;polarizationislittle.Socatalyticmembranemustbe ;thin.Inordertoimproveexterioractivation,catalytic ;membranecanbepreparedbythemixtureofelectric ;andpureactivecarbonandthebondswhichis ;composedofPTFE,distilledwaterandblacklead.The ;preparationofcatalyticmembraneisdescribedin ;Fig.2.

    ;Distilledwater

    ;l

    ;PTFE+

    ;AbsolutealcoholBlacklead

    ;lI

    ;EquablemixtureEquablemixture—Drying’Extractinginacetone ;Active

    ;f

    ;carbon土上

    ;Catalyticmembrane-Grindingin70—80~C’DippinginisopropanolDrying

    ;Fig.2Thepreparationofcatalyticmembrane ;Extractioninacetoneandgrindingin7080~Care

    ;alsothekeyfactorsinthepreparationofcatalytic ;membrane.

    ;3.3Thepreparationofcarbonelectrode

    ;Catalyticmembrane,waterproofbreathable

    ;membrane,electricnet,andwaterproofbreathable ;membranewereputonthemouldinturnandpressedat ;acertainpressure.Thencarbonelectrodewasprepared. ;ThestructureofcarbonelectrodeiSdescribedinFig.3. ;Waterproofbreathablemembrane

    ;Electricnet

    ;Waterproofbreathablemembrane

    ;Catalyticmembrane

    ;Fig.3Thestructureofcarbonelectrode

    ;Themouldingpressureisakeyfactorofthe

    ;preparationofcarbonelectrode.Toolittlepressure ;decreasesthestrengthofcarbonelectrode,whiletoo ;muchpressuredecreasestheporosityofcarbon ;electrodeandtheactivationofcatalyticmembrane.We ;concludedbyexperimentsthatthebestmoulding ;pressurewas400Kg/M.

    ;3.4Thechoiceofactivateddisposal

    ;temperature

    ;Thepropertyofcarbonelectrodecanbe

    ;improvedbythe.

    ;activateddisposalinsome

    ;temperature.Carbonelectrodewasfixedintheclamp, ;putinthemuffleanddisposedinsometemperature. ;Thenvolumeresistivityofcarbonelectrodewastested. ;ThetestingresultiSdescribedinTable1.

    ;Table1Volumeresistivityatdifferent

    ;disposaltemperature

    ;DisposalVolumeR

    ;emark

    ;temperature(?)resistivity(Q.m)

    ;3501.8001

    ;3800.9O66Thesame

    ;disposaltime

    ;SpecialO

    ;.6OHD2

    ;temperature

    ;FromTable1,weconcludedthatvolumeresistivity ;ofcarbonelectrodedisposedatspecialtemperaturewas ;lowest.Sooxygenconcentration,currentdensity,and ;operativelifetimeofelectrochemicaloxygengenerator ;whichisusingcarbonelectrodedisposedatspecial ;temperatureascathodearegreatlyimproved.Therefore ;carbonelectrodedisposedatSpecialtemperatureis ;adaptedtobeusedascathodeofelectrochemicaloxygen

;generator.

    ;4.Propertiestestingofcarbonelectrode

    ;4.1Testingofmechanicalpropertiesofcarbon

    ;electrode

    ;Thetensilesamplesofcarbonelectrodewhich

    ;includedtransversalandlongitudinalsampleswere ;prepared.Thetestingoftensilepropertiesofcarbon ;electrodewascarriedoutonelectronicuniversal ;59

    ;Thepreparationofhighperformancecarbonelectrodeinelectrochemicaloxygengenera

    ——

    ;tor

    ;materialtestingmachine.ThetestingdataisdescribeddescribedinFigs.4and5.

    ;inTable2andTable3.Thestressstraincurveis

    ;Table2Thetransversaltensiletestingofcarbonelectrode ;MaximumTensileBreakingBreakingStressatdefineElongationatN ;umberWidth1’hicknessAreal

    ;oadstrengthstrengthelongationelongationdefinestress ;(No)(ram)(mm)(ram)(N)fMPa)(MPa)(%)(MPa)(%) ;142.489.92l9.6621.9821.786l54.6651.9530.5l ;242.5210.0820.8762.0711.87l74.5952.04726.845 ;342.510l9.9081.99l1.805176.371.96629.45

    ;442.489.9220.632.081.876l67.9752.06323.79 ;Average42.59.9820.272.031.83168.42.Ol27.65 ;Standard0O

    ;.02O.O8O.580.050.()59.840.o63d

    ;eviation

    ;Maximum42.521O.0820.882.081.88176.372.O630.51 ;Minimum42.489.9219.661.981.79l54.671.9523.79 ;Table3Thelongitudinaltensiletestingofcarbonelectrode ;MaximumTensileBreakingBreakingStressatdefineElongationatN ;umberWidth11hicknessAlea1

    ;oadstrengthstrengthelongationelongationdefinestress ;(No)(ram)(ram)(ram)(N)(MPa)(MPa)(%)(MPa)(%) ;142.49.619.181.9981.8o4203.7851.964l.925

    ;242.51O173141.7311.56167.5051.6267.65

    ;342.541O.1615.6941.5451.394162.3551.4966.Ol ;442.581O.3218.694.8111.63l278.935.7830.48

    ;Average42.5110.0217.721.771.6203.151.7229.02 ;Standard0O

    ;.080.311.570.19O.1753.790.226.58d

    ;eviation

    ;Maximum42.581032I9.1821.8278.941.9666.Ol

    ;Minimum42.49.615.691.551.39162-361.497.65

;5O0

    ;Fig.4Stress?straincurveofcarbonelectrode(transversa1) ;60

    ;Fig.5Stress-straincurveofcarbonelectrode ;rlongitudina1)

    ;22llO

    ;

    ;Thepreparationofhighper

    ;

    ;formancecarbonelectrodeinelectrochemicaloxygengenerat0l?

    ;FromTables2and3,weconcludedthatthe

    ;transversalandlongitudinaltestingdataofcarbon ;electrodeweredifferent.Becauseelectricnetwas ;madefromcopperandtheholewaslozenge,thenet ;wasdirective.Thereforethetransversa1and ;longitudinalmechanicalpropertiesofcarbonelectrode ;weredifferent.FromFigs.4and5,Tables2and3,we ;concludedthatfilmofcarbonelectrodewasmore ;toughandlessintensivethanplastic.Butthefilmcould ;meetworkingrequirementofelectrochemicaloxygen ;generator.

    ;4.2Propertiestestingofelectrochemical ;oxygengenerator

    ;Theelectrochemicaloxygengeneratorwas ;composedofspumynickelusedasanode,carbon ;electrodewhichwasdisposedatspecialtemperature ;usedascathode,and30%sodiumhydroxidesolution ;usedaselectrolyte.Oxygenconcentrationofthis ;machinewas99.6%.whicharrivedatnationalstandard ;ofmedicaloxygen.InCN2321786

    ;,CN2210902,

    ;CN2198285I4].themostcurrentdensityofoxygen ;generatorwas5A/dm.Butthemostcurrentdensityof ;ouroxygengeneratorwas6A/dm.Furthermorethe ;machineworkedsafelyinsuchcurrentdensity.Oxygen ;flowofoxygengeneratorinpersquaredmwas1620

    ;mL/mininCN2210902.CN2198285andwas2430

    ;mL/mininCN2321786.HoweverOxygenflowofour ;machinewas405OmL/min.Thusitcanbeseenthat

    ;currentdensityandoxygenflowofouroxygen ;generatorishighestinthesametypeones.Becauseof ;specialbondandelectrobathused,operativelifetimeof ;ourmachineisprolongedandcanattainfiveyears. ;5.Conclusions

    ;Highperformancecarbonelectrodewasprepared. ;Itspropertywastested.Itwasappliedinthe ;electrochemicaloxygengenerator,andthenoxygen ;concentrationofthismachinewas99.6%.which ;arrivedatnationalstandardofmedicaloxygen. ;(1)Waterproofbreathablemembrane.electricnet ;andcatalyticmembranewereputintumandpressed. ;Thencarbonelectrodewasprepared.Ratioofraw ;material,extractioninacetone,grindingtechnology, ;mouldingpressure,andactivateddisposaltemperature ;hadaneffectonthepropertiesofcarbonelectrode. ;(2)Thefilmofcarbonelectrodewasmoretough ;andIessintensivethanplastic.Butthefilmcouldmeet ;workingrequirementofelectrochemicaloxygen ;generator.

    ;(3)Themostcurrentdensityofelectrochemical ;oxygengeneratorproducedbyuswas6A/din.Oxygen ;flowofourmachineinpersquaredmwas40-50

    ;mL/min.Socurrentdensityandoxygenflowof ;electrochemicaloxygengeneratorproducedbyusis ;highestinthesametypeones.

    ;6.Prospects

    ;Carbonelectrodecanbewidelyusedin

    ;electrochemicaloxygengenerator,fuelcell,zincair

    ;cell,aluminumaircell,magnesiumaircell,andsalt

    ;electroanalysis.Thereforethepreparationofhigh ;performancecarbonelectrodeisveryimportant.Inthe ;future,ourresearchwillemphasizethatoxygenflowof ;electrochemicaloxygengeneratorisimprovedby ;decreaseofvolumeresistivityonconditionthat ;waterproofbreathablepropertiesandcatalyticeffect ;ofcarbonelectrodejsn’taffected

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    ;【】molarconcentration,mol’m.’

    ;ttime,S

    ;kreactionratecoefficient.S

    ;areactionordersofphenol

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    ;11mmechanicalefficiency

    ;qRmolarreactionheat,kJ’mol

    ;Ttemperature.?

    ;Vi,

    ;pstoichiometriccoefficientofproducti

    ;vi.

    ;Rstoichiometficcoefficientofreactanti ;Bavailableenergy,kJ’kg

    ;Sospecificentropyatreferencestate,kJkg-I.K ;Hospecificenthalpyatgroundstate,kJ’kg

    ;(continuedfromPage61)

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    ;70

    ;specificentropy,kJ’kg-1.K’

;specificenthalpy,kJ’kg

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    ;pressureofstreamx,kPa

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    ;rateofmass.kg?S1

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    ;availableenergyconsumptionrate,kJ.kg’

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