Bromate removal by chemical reduction using iron (II)

82 Pages·2016·6.07 MB·English

Bromate removal by chemical
reduction using iron (II)

Optimizing AOP-MAR process

Vanida A. Salgado Ismodes
B
ROMATE REMOVAL BY CHEMICAL
(II)
REDUCTION USING IRON
OPTIMIZING AOP-MAR PROCESS
by
VanidaSalgadoIsmodes
inpartialfulfillmentoftherequirementsforthedegreeof
MasterofScience
inCivilEngineering
attheDelftUniversityofTechnology,
tobedefendedpubliclyonThursdayNovember17,2016at10:00AM.
Studentnumber: 4419227
Thesiscommittee: Prof.dr.J.P.vanderHoek, TUDelft
MSc.F.Wang, TUDelft
Dr.D.vanHalem, TUDelft
Dr.K.Lekkerkerker-Teunissen, Dunea
Prof.P.J.Stuyfzand, TUDelft
Anelectronicversionofthisthesisisavailableathttp://repository.tudelft.nl/.

A
CKNOWLEDGEMENTS
After2yearsand3monthstheendingofmyMSc. studieshascome. Ithasbeenanniceexperiencefullof
hardworkandstudiesbutthemostimportantthingIhavemetwonderfulpeople.
Thelast9monthsIhavebeenworkingonmythesisandithasbeenacontinuouslearningprocess. Thisre-
searchhasbeenfinishedandsucceeded,thankstothetechnicalsupport,supervisionandguidanceofFeifei
Wang,DorisvanHalemandProf. JanPetervanderHoek. Thanksforallyourideas,suggestionsandatthe
sametime,thespaceandfreedomthatyougavemetoconductthisstudyinthebestway.
IwouldalsoliketothanksBecasChile,becausemystudieswerefundedbyCONICYTPAI/INDUSTRIA79090016.
PeoplefromtheWaterlab(ArmandandMohammed)andHetWaterlaboratorium(Luc)thanksforreplying
mydoubts,helpingandprovidingmewiththeequipmentandmaterialsneededformythesis.
Devina,Nessia,Timon,Max,Alex,Victor,Frans,Agniandthespanishinterns,thanksforourconversations,
yourcompanyandtomakemydaysfunnierandeasierIenjoyedthetimethatwespenttogether.
DaviddeRidderthanksforhelpingmeandlendingmeyourthingsinthelaboratoryandforyourinteresting
chemicalconversations,Ienjoyedthem.
Last but not least, my family and Juan, I could not be able to do this without you. Thanks for your help,
support,patienceandconfidenceinmeduringthisyears,fromtheverybeginning(sincemyapplicationto
TUDelft).PapiandmamithanksforalwaysbelieveinmeandmakemebelievethatIcanachievemydreams.
Kellyafterallthethingsthatyouhavepassedthrough,youhaveshowedmethatnothingisimpossibleand
everythingcanbeachievedwithperseverance,effort,loveandgoodmood.Juanthanksforbeingpatientand
havewaitedforme.
iii

S
UMMARY
Thisstudyinvestigatedtheremovalofbromate, asaby-productofAOP,bychemicalreductionusingiron
(II),andthepossibilityofusingthistechnologyasawatertreatmentorduringthemanagedaquiferrecharge
(MAR).Fiveexperimentswerecarriedoutunderanoxicconditionsat12°CandpH9.5toevaluatethebromate
reductionathigh(5mg/L)andlow(60µg/L)concentrationswithdifferentiron(II)doses(13and52mg/L
forhighbromateconcentrationand0.15and1.5mg/Lforlowbromateconcentration),inthepresenceand
absenceofnitrate(5and10mg/L).Thelowirondosesaresimilartotheconcentrationsfoundinthedunes.
Inaddition0.15mg/Lwasselectedaccordingtothestoichiometryrelationnecessarytoreduce60µg/Lbro-
mate.Forthehighironconcentrations,13mg/Lwaschosenbasedonthestoichiometryrelationneededfor
5mg/L.Inaddition,nitratereductionbyironinabsenceofbromatewasevaluatedwithandwithoutcatalyst.
Forthehighbromateconcentration,90%ofbromatewasreducedby13mg/Liron(II)afterthe5ththeday
inpresenceandabsenceofnitrate,whilewith52mg/Lirondoseallthebromatewasreducedwithinthefirst
30mininabsenceofnitrateand2hoursinthepresenceofnitrate.Bromatewasfavoredbyironovernitrate
inthepresenceofequalanddifferentconcentrations.
Thereductionoflowconcentrationsofbromatewasslow.After5days12%ofbromatewasreducedwith0.15
mg/Lirondoseinthepresenceofnitrate,while7%ofbromatewasreducedwiththesameirondoseinthe
absenceofnitrate. The1.5mg/Lirondosereduced58and75%ofbromateinthepresenceandabsenceof
nitrate,respectively.
Moreover,theexperimentsofnitrateinabsenceofbromateshowedthatnitratewasnotreducedbyiron(II).
Thereductionofbromatebyiron(II)stronglydependsontheirondoseandthereactiontime,thereforethis
technologycouldbeusedasawatertreatmenttechnologyincreasingtheirondosetoreducethereaction
timeortakingthecharacteristicsofMAR(anoxicenvironmentwithiron(II)contentandlongresidencetime)
asanadvantagewhichwouldbepropitiousforbromatereduction.
v

C
ONTENTS
1 Introduction 1
1.1 AdvancedoxidationprocessAOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Bromateformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Bromateremoval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Chemicalreductionwithiron(II). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.5 Scopeofthisthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.6 Researchquestions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Materialsandmethods 7
2.1 Experimentalconditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Preparationofsolutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 RedoxBatchexperiments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3.1 Bromatereductionbytwoiron(II)dosesattwodifferentpH . . . . . . . . . . . . . . . 8
2.3.2 Nitratereductionbyiron(II)withandwithoutcatalyst . . . . . . . . . . . . . . . . . . 9
2.3.3 Bromatereductionbyhighiron(II)concentrations,inthepresenceofnitrate. . . . . . . 9
2.3.4 Bromatereductionbylowiron(II)concentrations,inthepresenceofnitrate . . . . . . . 10
2.3.5 Bromatereductionbytwoiron(II)doses(similartodunes) . . . . . . . . . . . . . . . . 11
2.3.6 Measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3.7 Statisticalanalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3 Results 13
3.1 Bromatereductionbytwoiron(II)dosesattwodifferentpH. . . . . . . . . . . . . . . . . . . 13
3.1.1 ThetwoIron(II)doses:individualbehaviourdetails. . . . . . . . . . . . . . . . . . . . 13
3.1.2 Interactioneffectsbetweenirondoses,pH andreactiontime . . . . . . . . . . . . . . . 16
3.1.3 Maineffectsofirondoses,pH andreactiontime . . . . . . . . . . . . . . . . . . . . . 17
3.2 Nitratereductionbyiron(II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.3 Bromatereductionbyhighiron(II)concentrations,inthepresenceofnitrate . . . . . . . . . . 19
3.3.1 Interactioneffectbetweenirondosesandreactiontime. . . . . . . . . . . . . . . . . . 20
3.4 Bromatereductionbylowiron(II)concentrations,inthepresenceofnitrate. . . . . . . . . . . 21
3.4.1 Irondose0.007mM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.4.2 Irondose0.03mM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.4.3 Interactioneffectbetweenirondosesandreactiontimeatlowconcentrationinpres-
enceofnitrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.5 Bromatereductionbylowiron(II)concentrations,intheabsenceofnitrate . . . . . . . . . . . 24
3.5.1 Irondose0.007mM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.5.2 Irondose0.03mM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.5.3 Interactioneffectbetweenirondosesandreactiontimeatlowconcentration. . . . . . . 26
3.6 Comparisonofbromatereductioninpresenceandabsenceofnitrate . . . . . . . . . . . . . . 27
3.6.1 Highconcentrationofbromate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.6.2 Lowconcentrationofbromate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.7 AdjustingKineticsforlowBromateconcentration . . . . . . . . . . . . . . . . . . . . . . . . 30
4 Discussion 33
4.1 Bromatereductionbytwoiron(II)dosesattwodifferentpH. . . . . . . . . . . . . . . . . . . 33
4.2 Bromatereductionbyhighiron(II)concentrations,inthepresenceofnitrate . . . . . . . . . . 34
4.2.1 Reductioncapabilityofbromateandnitrate. . . . . . . . . . . . . . . . . . . . . . . . 34
4.3 Reductionoflowconcentrationofbromateinpresenceandabsenceofnitratewithtwoiron
doses(similartodunes). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.4 Bromatereduction:watertreatmenttechnologyormanagedaquiferrecharge(MAR)? . . . . . . 36
4.4.1 WatertreatmentTechnology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.4.2 MAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
vii
viii CONTENTS
5 Conclusions 41
Bibliography 43
A Bromateremovaltechnologies 47
A.1 ActivatedcarbonAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
A.1.1 ACcharacteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
A.1.2 pH effect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
A.1.3 PresenceofNOMandanions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
A.2 Modifiedactivatedcarbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
A.2.1 Bimetallicactivatedcarbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
A.2.2 PolypyrroletailoredAC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
A.2.3 NanoironhydroxideimpregnatedGAC(Fe-GAC) . . . . . . . . . . . . . . . . . . . . . 50
A.3 Iron. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
A.3.1 Granularferrichydroxide(GFH). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
A.3.2 Zerovalentironimmobilizedonfunctionalpolypropylenefiber. . . . . . . . . . . . . . 51
A.3.3 Nanocrystallineakaganeite(β−FeOOH)-coatedquartzsand(CACQS). . . . . . . . . . 51
A.4 Layereddoublehydroxides(LDH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
A.4.1 Anionsremoval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
A.4.2 Grapheneoxidenanosheetsaswaterseparationmembranes . . . . . . . . . . . . . . . 54
A.4.3 TiO (P25)-graphene(photocaltalyticdecomposition) . . . . . . . . . . . . . . . . . . 55
2
A.4.4 Graphenenanozero-valentironcomposites. . . . . . . . . . . . . . . . . . . . . . . . 56
−
A.4.5 Graphene-modifiedPd/CcathodeandPd/GAC(electrocatalyticremovalofBrO ) . . . . 56
3
A.5 Zeolites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
A.6 Hydroxyapatite(HAP). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
B Calculationsforchemicalsolutions 59
B.1 FeSO solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4
B.1.1 13.125mg/L(0.27mM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
B.1.2 52.5mg/L(1mM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
B.1.3 0.15mg/L(0.007mM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
B.1.4 1.5mg/L(0.03mM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
B.2 Bromatesolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
B.2.1 5mg/L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
B.2.2 60mg/L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
B.3 Nitrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
B.3.1 5mg/L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
B.3.2 2.8mg/L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
B.3.3 7.8mg/L. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
B.4 2mM NaHCO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3
B.5 Copper(II)solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
B.5.1 1.28mg/L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
C Visualregisterofironoxidation 63
C.1 Bromatereductionbytwoiron(II)dosesattwodifferentpH . . . . . . . . . . . . . . . . . . . 63
C.2 Nitratereductionbyiron(II)dosagewithandwithoutcatalyst . . . . . . . . . . . . . . . . . . 65
C.3 Bromatereductionbyhighiron(II)concentrations,inthepresenceofnitrate . . . . . . . . . . 66
C.4 Bromatereductionbylowiron(II)concentrations,inthepresenceofnitrate . . . . . . . . . . 68
C.5 Bromatereductionbylowiron(II)concentrations,intheabsenceofnitrate . . . . . . . . . . . 69
D Nitratereductionbyiron(II)andcatalyst 71
1
I
NTRODUCTION
1.1. ADVANCED OXIDATION PROCESS AOP
Disinfectionisusedindrinkingwatertreatmenttopreventwaterbornediseaseandkillorinactivatepathogens
microorganisminwatersupplies.Chlorineisthemostwidelyuseddisinfectantsince1900.However,in1974,
researchersinNetherlandsandUnitedStatesdemonstratedthatwaterchlorinationcauseformationoftri-
halomethanesthroughareactionbetweenchlorineorbromidewithorganicmatter[1].InTheNetherlands,
theAssociationofDutchWaterCompanies(Vewin)setthresholdvaluesfortrihalomethanes,andin2008the
standardvaluesbecamestricterwhileifchlorinationwasuseditwasnotpossibletofulfillthem.Inaddition,
itwasfoundthatCryptosporidium,GiardiaandLegionellawereresistanttochlorination.
Moreover,organicmicropollutantsOMPsincludediversechemicalcompounds,suchaspesticides,pharma-
ceutical,personalcareproductsamongotherswhichenterintotheenvironmentthroughdischargesfrom
wastewatertreatmentplants,industriesandhospitals,agriculturalrun-offandlandfillleachates[2,3].OMPs
havebeenfoundinsurfacewatersaroundtheworld. OMPsarenotnewbutthedevelopmentofmoreaccu-
ratetechniqueswithlowdetectionlimitsallowsthatmoreOMPscanbedetected,emergingquestionsabout
their effects on human health. Although, there is no evidence that most pharmaceuticals have a human
healthrisk,themixtureofthemandthepresenceofcarcinogensOMPsevenatlowconcentrationsisacon-
cernforhumanhealth[4],especiallybecausethesecompoundsdonotbelongtodrinkingwater.
TheneedofdisinfectwaterandremoveOMPstriggeredthedevelopmentofalternativetreatmentsasoxida-
tiontechniquesdefinedasadvancedoxidationprocesses(AOP)whicharecapableofexploitthehighreac-
tivityofhydroxylradicals(OH°)inoxidationprocesstoachievecompleteabatementofpollutants[5]. The
most common AOP and suitable for water treatment areUV/H O , H O /O ,UV/O ,UV/H O /O or
2 2 2 2 3 3 2 2 3
UV/TiO [6,7]. Moreover,ithasbeenproventhatadvancedoxidationprocesscaninactivateawiderrange
2
ofmicroorganismssuchasprotozoaandvirusesthanconventionaldisinfectants(chlorine,dioxidechlorine)
[8].Inaddition,AOPwilloxidizeparentcompoundsintocarbondioxideandwaterorintosmallermolecules
thataremoreeasilybiodegradable[3]. Furthermore,watersupplierstreatdrinkingwatertoprotectpublic
healthandprovidewaterwithouttasteorodour.
Ozonationfulfillstheserequirementsbecauseitcancontroltasteandodour,removethecolourcausedby
humicsubstances,disinfectthewaterthroughinactivatingbacteria,cysts,virusesandtransformOMPsinto
simplermolecules[4]. However, ithasbeenreportedthatinbromide-containingwaters, theformationof
manyby-productsoccursduringozonation,suchasbromate[8,9]. AccordingtotheInternationalAgency
forResearchonCancer-IARC,bromatehasbeenclassifiedinGroup2Basapossiblecarcinogenictohumans.
Furthermore, the World Health Organization-WHO has indicated that bromate is mutagenic both in vitro
andinvivo[10]. Thereforetheformationofby-products,inthiscase,bromate,needstobeevaluatedcare-
fully. Duetotheharmfuleffectsofbromate,theWHOandEnvironmentalProtectionAgency-EPAhaveseta
drinkingwaterstandardof10µg/Lforbromate. However,theDutchDrinkingWaterguidelineindicatesfor
oxidation1µg/L or5µg/L fordisinfection[11]. Therefore,theinterestofdevelopingnewtechnologiesto
achievetheselowlimitsindrinkingwaterhasincreasedinthelastyears.
1