RamPrasad •
ThirugnanasambandhamKarchiyappan Editors
AdvancedResearch inNanosciencesforWater Technology
Editors RamPrasad SchoolofEnvironmentalScience andEngineering
SunYat-senUniversity
Guangzhou,China
AmityInstituteofMicrobialTechnology
AmityUniversityUttarPradesh Noida,UP,India
ThirugnanasambandhamKarchiyappan StateUniversityofMaringa Paraná,Paraná,Brazil
ISSN2523-8027ISSN2523-8035(electronic)
NanotechnologyintheLifeSciences
ISBN978-3-030-02380-5ISBN978-3-030-02381-2(eBook) https://doi.org/10.1007/978-3-030-02381-2
LibraryofCongressControlNumber:2018963720
© SpringerNatureSwitzerlandAG2019
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Preface
Establishmentofclean,safewaterisoneofthemajorchallengesfacedaroundthe world.Thecontinuedurbanizationofhumanpopulations,theincreasingmanipulationofnaturalresources,andtheresultingpollutionareplacingaremarkableburden onwaterresources.Increasingdemandsforfood,energy,andnaturalresourcesare expectedtocontinuetoaccelerateintothenearfutureinresponsetothedemandsof changinghumanpopulations.Inaddition,thecomplexityofhumanactivitiesis leadingtoadiversityofnewchemicalcontaminantsintheenvironmentthatpresent amajorconcernforwatermanagements.Thiswillcreateincreasedpressureonboth waterquantityandquality,makingitincreasinglydifficulttoprovideasustainable supplyofwaterforhumanwelfareandactivities.
Duetotheiruniquephysico-chemicalproperties,nanotechnologiesareextensivelyusedinantibacterials(medicalproducts),membrane filters,electronics,photo catalysts,andbiosensors.Nanoparticlescanhavedistinctlydifferentpropertiesfrom theirbulkcounterparts,creatingtheopportunityfornewmaterialswithadiversityof applications.Recentdevelopmentsrelatedtowatertreatmentincludethepotential useofquantumdots,nanocomposite,nanospheres,andnanowiresfortheremovalof adiversityofchemicalpollutants.Byexploitingtheassetsandstructureofthesenew materials,suchasincreasedsurfacearea,highreactivity,andphotocatalyticaction,it willbepossibletocreatetechnologiesthatcanbeveryefficientatremovingand degradingenvironmentalpollutants.Understandingandusingtheseuniquepropertiesshouldleadtoinnovative,cost-effectiveapplicationsforaddressingthecomplexitiesoftheemergingneedsforwastewatertreatment.
Thebook AdvancedResearchinNanosciencesforWaterTechnology comprises 19chapterswrittenbytheexpertsinthis field,highlightinglatestresearchon nanosciencesuchasapplicationsofnanotechnologyforwastewatertreatment, bioenergygenerationinmicrobialfuelcells,waterpurification,heavymetal removal,andoil–watertreatment.Withafortuneofinformationondifferentaspects ofnanotechnology,thisextensivevolumeisavaluableresourceforresearchers, academicians,policymakers,andstudentsinvarious fieldssuchasmicrobiology, nanotechnology,andenvironmentalscience.
Wearehighlydelightedandthankfultoallourcontributingauthorsfortheir supportandactivecooperationintheirwritingofthesevaluablechapters.Ram Prasadextendssincerethankstoallourcolleagueswhohelpedusinthepreparation ofthegenerousvolume.WethankSpringerofficials,especiallyEricStannard, AnthonyDunlap,RahulSharma,andGomathiMohanarangan,fortheirgenerous supportandeffortstoaccomplishthisvolume.
Noida,UttarPradesh,IndiaRamPrasad Paraná,Paraná,BrazilThirugnanasambandhamKarchiyappan
Contents
1EconomicAssessmentofNanomaterialsinBio-Electrical WaterTreatment ......................................1 MichaelSiegert,JayeshM.Sonawane,ChizobaI.Ezugwu, andRamPrasad
2BioconjugatedQuantumDotsinRapidDetection ofWaterMicrobialLoad:AnEmergingTechnology ...........25 InduPalKaur,JogaSingh,JatinderV.Yakhmi,GurpalSingh, CorinneDejous,AlkaBhatia,AshishSattee,andUditSoni
3WaterPollutionRemediationTechniqueswithSpecialFocus onAdsorption .........................................39 SujataMandal,C.Muralidharan,andAsitBaranMandal
4EffectofNano-TiO2 ParticlesonMechanicalProperties ofHydrothermalAgedGlassFiberReinforcedPolymer Composites ...........................................69 RameshKumarNayak
5Nanotechnology:AnInnovativeWayforWastewater TreatmentandPuri fication ...............................95 MuhammadRafique,MuhammadBilalTahir,andIqraSadaf
6ImmobilizedNanocatalystsforDegradationofIndustrial Wastewater ...........................................133 JayaseelanArun,MarudaiJoselynMonica,VargeesFelix, andKannappanPanchamoorthyGopinath
7NewTechnologiestoRemoveHalidesfromWater: AnOverview ..........................................147 JoséRivera-Utrilla,ManuelSánchez-Polo,AnaM.S.Polo, JesúsJ.López-Peñalver,andMaríaV.López-Ramón
8NanotechnologyExploredforWaterPuri fication ..............181 A.Laha,D.Biswas,andS.Basak
9NanomaterialsintheDevelopmentofBiosensorandApplication intheDeterminationofPollutantsinWater ..................195 GermánA.Messina,MatíasRegiart,SirleyV.Pereira, FrancoA.Bertolino,PedroR.Aranda,JulioRaba, andMartínA.Fernández-Baldo
10Clay-BasedNanocomposites:PotentialMaterials forWaterTreatmentApplications .........................217 FaraanFareed,M.Ibrar,YaseenAyub,RabiaNazir, andLubnaTahir
11ApplicationofNano-PhotocatalystsforDegradation andDisinfectionofWastewater ............................249 JayaseelanArun,VargeesFelix,MarudaiJoselynMonica, andKannappanPanchamoorthyGopinath
12DegradationofEmergingContaminantsUsingFe-Doped TiO2 UnderUVandVisibleRadiation ......................263 IrwingM.Ramírez-Sánchez,OscarD.Máynez-Navarro, andErickR.Bandala
13OxideNanomaterialsforEfficientWaterTreatment ............287 AlagappanSubramaniyan
14NanotechnologyforOil-WaterSeparation ...................299 PrakashM.Gore,AnukrishnaPurushothaman,MinooNaebe, XungaiWang,andBalasubramanianKandasubramanian
15NanotechnologyforWastewaterTreatmentandBioenergy GenerationinMicrobialFuelCells .........................341 M.J.Salar-GarcíaandV.M.Ortiz-Martínez
16NanocompositeMaterialsBasedonTiO2/Clay forWastewaterTreatment ...............................363 SoulaimaChkirida,NadiaZari,AbouElKacemQaiss, andRachidBouhfid
17Nanotechnology:TheTechnologyforEfficient,Economic, andEcologicalTreatmentofContaminatedWater .............381 S.VijayakumarandM.Priya
18SilverNanoparticlesasaBiocideforWaterTreatment Applications ..........................................407 RenatR.Khaydarov,RashidA.Khaydarov,OlgaGapurova, IlnurGaripov,andM.Lutfi Firdaus
Contributors
PedroR.Aranda InstitutodeQuímicadeSanLuis(INQUISAL) Consejo
NacionaldeInvestigacionesCientíficasyTécnicas(CONICET),Universidad NacionaldeSanLuis(UNSL),SanLuis,Argentina
JayaseelanArun DepartmentofChemicalEngineering,SSNCollegeof Engineering,Kalavakkam,TamilNadu,India
YaseenAyub GovernmentIslamiaCollegeCivilLines,Lahore,Pakistan
ErickR.Bandala DesertResearchInstitute(DRI),LasVegas,NV,USA
S.Basak IndianCouncilofAgriculturalResearch,CentralInstituteforResearchon CottonTechnology(CIRCOT),Mumbai,Maharashtra,India
FrancoA.Bertolino InstitutodeQuímicadeSanLuis(INQUISAL) Consejo
NacionaldeInvestigacionesCientíficasyTécnicas(CONICET),Universidad NacionaldeSanLuis(UNSL),SanLuis,Argentina
AlkaBhatia DepartmentofExperimentalMedicineandBiotechnology,PGIMER, Chandigarh,India
D.Biswas IndianJuteIndustriesResearchAssociation,Kolkata,WestBengal, India
RachidBouhfid LaboratoryofPolymerProcessing,MoroccanFoundationfor AdvancedScience,InnovationandResearch(MAScIR),InstituteofNanomaterials andNanotechnology(NANOTECH),Rabat,Morocco
JayeetaChattopadhyay DepartmentofChemistry,AmityUniversityJharkhand, Ranchi,Jharkhand,India
SoulaimaChkirida LaboratoryofPolymerProcessing,MoroccanFoundationfor AdvancedScience,InnovationandResearch(MAScIR),InstituteofNanomaterials andNanotechnology(NANOTECH),Rabat,Morocco
CorinneDejous UniversitedeBordeaux,IMS,ENSEIRB,CNRSUMR5218, Talence,France
AbouElKacemQaiss LaboratoryofPolymerProcessing,MoroccanFoundation forAdvancedScience,InnovationandResearch(MAScIR),Instituteof NanomaterialsandNanotechnology(NANOTECH),Rabat,Morocco
ChizobaI.Ezugwu SchoolofEnvironmentalScienceandEngineering,Sun Yat-senUniversity,Guangzhou,China
FaraanFareed GovernmentCollegeofScience,Lahore,Pakistan
VargeesFelix DepartmentofChemicalEngineering,SSNCollegeofEngineering, Kalavakkam,TamilNadu,India
MartínA.Fernández-Baldo InstitutodeQuímicadeSanLuis(INQUISAL) –ConsejoNacionaldeInvestigacionesCientíficasyTécnicas(CONICET), UniversidadNacionaldeSanLuis(UNSL),SanLuis,Argentina
OlgaGapurova InstituteofNuclearPhysics,UzbekistanAcademyofSciences, Tashkent,Uzbekistan
IlnurGaripov InstituteofNuclearPhysics,UzbekistanAcademyofSciences, Tashkent,Uzbekistan
KannappanPanchamoorthyGopinath DepartmentofChemicalEngineering, SSNCollegeofEngineering,Kalavakkam,TamilNadu,India
PrakashM.Gore NanoSurfaceTexturingLab,DepartmentofMetallurgical& MaterialsEngineering,DIAT(DU),MinistryofDefence,Pune,Girinagar,India
InstituteforFrontierMaterials,DeakinUniversity,Geelong,VIC,Australia
M.Ibrar LahoreGarrisonUniversity,Lahore,Pakistan
BalasubramanianKandasubramanian NanoSurfaceTexturingLab,Department ofMetallurgical&MaterialsEngineering,DIAT(DU),MinistryofDefence,Pune, Girinagar,India
InduPalKaur UniversityInstituteofPharmaceuticalSciences,PanjabUniversity, Chandigarh,India
RashidA.Khaydarov InstituteofNuclearPhysics,UzbekistanAcademyof Sciences,Tashkent,Uzbekistan
RenatR.Khaydarov InstituteofNuclearPhysics,UzbekistanAcademyof Sciences,Tashkent,Uzbekistan
A.Laha RelianceIndustryLtd.,NaviMumbai,Maharashtra,India
JesúsJ.Lopez-Peñalver FacultyofScience,DepartmentofInorganicChemistry, UniversityofGranada,Granada,Spain
MaríaV.López-Ramón FacultyofExperimentalScience,Departmentof InorganicandOrganicChemistry,UniversityofJaén,Jaén,Spain
M.Lutfi Firdaus GraduateSchoolofScienceEducation,UniversityofBengkulu, Bengkulu,Indonesia
AsitBaranMandal CSIR-CentralLeatherResearchInstitute,Chennai, TamilNadu,India
SujataMandal CLRI-CentreforAnalysis,Testing,EvaluationandReporting Services(CATERS),CSIR-CentralLeatherResearchInstitute,Chennai, TamilNadu,India
OscarD.Máynez-Navarro UniversidaddelasAméricasPuebla(UDLAP), Ex-HaciendaSantaCatarinaMártir,Cholula,Puebla,Mexico
GermánA.Messina InstitutodeQuímicadeSanLuis(INQUISAL) – Consejo
NacionaldeInvestigacionesCientíficasyTécnicas(CONICET),Universidad NacionaldeSanLuis(UNSL),SanLuis,Argentina
MarudaiJoselynMonica DepartmentofChemicalEngineering,SSNCollegeof Engineering,Kalavakkam,TamilNadu,India
C.Muralidharan LeatherProcessingDepartment,CSIR-CentralLeatherResearch Institute,Chennai,TamilNadu,India
MinooNaebe InstituteforFrontierMaterials,DeakinUniversity,Geelong,VIC, Australia
RameshKumarNayak SchoolofMechanicalEngineering,KIIT,Deemedtobe University,Bhubaneswar,Odisha,India
RabiaNazir PakistanCouncilofScientificandIndustrialResearchLabsComplex, AppliedChemistryResearchCentre,Lahore,Pakistan
V.M.Ortiz-Martínez DepartmentofChemicalandEnvironmentalEngineering, CampusMuralladelMar,TechnicalUniversityofCartagena,Cartagena,Spain DepartmentofChemicalEngineering,CampusEspinardo,UniversityofMurcia, Murcia,Spain
SirleyV.Pereira InstitutodeQuímicadeSanLuis(INQUISAL) – Consejo NacionaldeInvestigacionesCientíficasyTécnicas(CONICET),Universidad NacionaldeSanLuis(UNSL),SanLuis,Argentina
AnaM.S.Polo FacultyofScience,DepartmentofInorganicChemistry,University ofGranada,Granada,Spain
RamPrasad SchoolofEnvironmentalScienceandEngineering,SunYat-sen University,Guangzhou,China
M.Priya DepartmentofScienceandHumanities,SriRamakrishnaInstituteof Technology,Coimbatore,TamilNadu,India
AnukrishnaPurushothaman CentreforBiopolymerScienceandTechnology, CentralInstituteofPlasticsEngineeringandTechnology,Eloor,Udyogmandal, Kochi,India
JulioRaba InstitutodeQuímicadeSanLuis(INQUISAL) – ConsejoNacionalde InvestigacionesCientí ficasyTécnicas(CONICET),UniversidadNacionaldeSan Luis(UNSL),SanLuis,Argentina
MuhammadRafique DepartmentofPhysics,UniversityofGujrat,Gujrat, Pakistan
IrwingM.Ramírez-Sánchez DepartmentofCivil,ArchitecturalandEnvironmentalEngineering,TheUniversityofTexasatAustin,Austin,TX,USA
MatíasRegiart InstitutodeQuímicadeSanLuis(INQUISAL) – ConsejoNacional deInvestigacionesCientíficasyTécnicas(CONICET),UniversidadNacionaldeSan Luis(UNSL),SanLuis,Argentina
JoséRivera-Utrilla FacultyofScience,DepartmentofInorganicChemistry, UniversityofGranada,Granada,Spain
IqraSadaf DepartmentofPhysics,UniversityofGujrat,Gujrat,Pakistan
M.J.Salar-García DepartmentofChemicalandEnvironmentalEngineering, CampusMuralladelMar,TechnicalUniversityofCartagena,Cartagena,Spain DepartmentofChemicalEngineering,CampusEspinardo,UniversityofMurcia, Murcia,Spain
ManuelSánchez-Polo FacultyofScience,DepartmentofInorganicChemistry, UniversityofGranada,Granada,Spain
AshishSattee FacultyofAppliedMedicalSciences,DepartmentofPharmacognosyandPhytochemistry,LPU,Phagwara,Punjab,India
MichaelSiegert IndependentInvestigator,Chicago,IL,USA
GurpalSingh UniversityInstituteofPharmaceuticalSciences,PanjabUniversity, Chandigarh,India
JogaSingh UniversityInstituteofPharmaceuticalSciences,PanjabUniversity, Chandigarh,India
JayeshM.Sonawane IITB-MonashResearchAcademy,IndianInstituteof TechnologyBombay,Mumbai,India
UditSoni DepartmentofBiotechnology,TeriSchoolofAdvancedStudies,New Delhi,India
AlagappanSubramaniyan DepartmentofPhysics,ThiagarajarCollegeof Engineering,Madurai,TamilNadu,India
LubnaTahir GovernmentIslamiaCollegeCivilLines,Lahore,Pakistan
MuhammadBilalTahir DepartmentofPhysics,UniversityofGujrat,Gujrat, Pakistan
S.Vijayakumar DepartmentofScienceandHumanities,SriRamakrishnaInstitute ofTechnology,Coimbatore,TamilNadu,India
XungaiWang InstituteforFrontierMaterials,DeakinUniversity,Geelong,VIC, Australia
JatinderV.Yakhmi FormerlyatBhabhaAtomicResearchCentre,Mumbai,India
NadiaZari LaboratoryofPolymerProcessing,MoroccanFoundationfor AdvancedScience,InnovationandResearch(MAScIR),InstituteofNanomaterials andNanotechnology(NANOTECH),Rabat,Morocco
Chapter1
EconomicAssessmentofNanomaterials inBio-ElectricalWaterTreatment
MichaelSiegert,JayeshM.Sonawane,ChizobaI.Ezugwu,andRamPrasad
Contents
1.1Introduction.................................................................................1 1.2EconomicAssessmentofBESMaterials
1.1Introduction
Threepercentoftheelectricityconsumptioninfullyindustrializedcountriesis accountedforbywastewatertreatment(McCartyetal. 2011;RothausenandConway 2011).InChinaandotherdevelopingcountries,thisvalueisroughly1.5%
M.Siegert(*) IndependentInvestigator,Chicago,IL,USA e-mail: michael@siegert.org
J.M.Sonawane IITB-MonashResearchAcademy,IndianInstituteofTechnologyBombay,Mumbai,India
C.I.Ezugwu·R.Prasad SchoolofEnvironmentalScienceandEngineering,SunYat-senUniversity,Guangzhou,China
© SpringerNatureSwitzerlandAG2019
R.Prasad,K.Thirugnanasambandham(eds.), AdvancedResearchinNanosciences forWaterTechnology,NanotechnologyintheLifeSciences, https://doi.org/10.1007/978-3-030-02381-2_1
Fig.1.1 Possiblecostsavingsandpowersurplusfrommicrobialelectrolysisforanidealindustrial wastewatertreatmentplant(WWTP)scenario,using5.8MWhd 1 fortreating200m3 ofhigh strengthwastewater.Savingsinboldfontarebasedon80%CODremoval
(China:100TWh;Wang 2013)forthetreatmentof6000TWh(CentralIntelligence Agency 2017)totalproduction.Muchofthewastewaterproducedindeveloping countriesisstilldischargeduntreated(Liangetal. 2018).Atthesametime,thereuse ofwastewaterresourcescanturntreatmentfacilitiesintonetenergyproducers(Shizas andBagley 2004).Severaltechnologiesareabletoaccomplishthiswithanaerobic membranebedreactors(AnMBR)beingthemostmature(vanLieretal. 2016). Anotherpromisingfuturetechnologyisbio-electricalsystems(BES).Dependingon thequalityofthewastewater,allofthesetechnologiesroutinelyremovemorethan80% chemicaloxygendemand(COD)andrecovertherespectiveenergyamount.COD reductionandenergyrecoveryresultinsubstantialsavingsduringtheconstructionand operationofwastewatertreatmentplants(WWTP;Fig. 1.1).Throughoutthisarticle,we usemarketpricesof$0.06kWh 1 and$3MMBtu 1 asbaselineforourtechnoeconomicassessment.Materialcostswereextractedfromtherespectivepublications, orinquiredfrommanufacturersandretailerseitherthroughquotationsorInternet offers.UnlikeinmostpreviouscostassessmentsofBEStechnologies,weuseda scalingcoefficientof0.6toaccountforcapitalexpenditurediscountsinlarge-scale applicationsbutadmitthatthisissomewhatarbitrary(TribeandAlpine 1986).Wealso includesavingsof80%incurredfromreducedCODloadingafterBEStreatment.
TwodifferenttypesofBESarepossible(Fig. 1.2),microbialfuelcells(MFC)and microbialelectrolysiscells(MEC).MFCsdirectlyharvestelectricalpowerusing wastewaterorganicsasfuel,withoxygenasterminalelectronacceptor.The
Fig.1.2 Schematicofabio-electricalsystem(BES)intheformofaso-calledH-cell.TheBEScan beoperatedinelectrolysismodewithapowersupply,orinfuelcellmodewitharesistorconnecting bothelectrodes.Theelectrodesmaybeofthesamematerialandshapebuttheyareusuallydifferent astheycarryoutdifferentreactions,shownonthebottom.Eachelectrodemaybepoisedtoan electrochemicalpotentialrelativetoareferenceelectrode.Thereferenceelectrodeisoptionaland maybeusedformonitoringpurposesonly,e.g.,infuelcellmode.Amembranemayseparateboth chambersoftheH-cell.Ox,oxidant,Red,reductant
technologyhasbeenknownformorethanacenturyandwasheavilyinvestigated duringthelasttwodecades(Potter 1911;Heetal. 2005;LoganandRabaey 2012). Despitetheseefforts,powerdensitiesremainlowcomparedwithconventional hydrogenfuelcells.Thissituationmightbeimprovedusingbettermaterialsfor electrodesandmembranes.MECsexperiencedtwostagesofdiscovery, firstcathodic nitratereductionwasreportedbySakakibaraandKuroda(1993).Fifteenyearslater, organicmatterdegradationcoupledtohydrogenproductionwasdiscoveredby RozendalandBuisman(2010).ThedifferenceofMECstoMFCsisthatasmall voltageisapplied,whichimprovesreactionkineticsandmakesiteasiertocontrolthe treatmentprocess.Asaresult,hydrogengasisproducedwhichisthenconvertedinto methane(KurodaandWatanabe 1995).Theprocessisnaturallyexergonicandcalled acetoclasticmethanogenesis,assumingthatacetateisthesubstrate:
Theapplicationofasmallelectricalpotentialtothereaction,forexample,0.7V, drasticallyimprovestheenergybalanceforacetoclasticmicrobesbyadditional 540kJmol 1 (CH4),andhencealsomicrobialreactionkinetics.Ultimately,this
leadstoshorterhydraulicretentiontimes(HRTs)andabout20timessmaller reactors,occupyingfourtimeslessarea.WhilesizereductionmakesMECsmore attractivecomparedwithMFCs,downstreamcombustionofproducedgases,usually methane,inturbinesoccursatnotoriouslylowenergyefficienciesbetween30and 40%.Incontrast,thedirectconversionofwastewaterenergyintoelectricityinMFCs eliminatestheneedforinefficientcombustionsteps.
Despiteintensiveresearchandalonghistory,BEStechnologyisstillinits infancy.WhiletherehavebeensomeattemptstocommercializeBESforwastewater treatment,thereisstillroomforimprovement.ForMFCs,thisisarguablypower densityandforMECsitisgasproduction,whichultimatelytranslatesintopower densityaswell.Wethereforesuggesttousedollarperpeakpowercapacity($Wp 1) asabenchmarkforcostassessment.Dollarperpowerproduction($[Ws] 1)would stillbebetterbutsuchdataareusuallynotreported.Nanomaterialsarepromising leadstosolvetheproblemofpowerdensityinwastewaterBES.Therearethree differenttypesofnanomaterialsthatcanpotentiallybeusedinBES:carbon-based, metal-based,andmineralnanomaterials.Thesematerialsmaybeinsuspension, electrodedeposits,orinmembranes.Dependingonthelocation,theyservedifferent purposes.Onelectrodestheymayimproveattachmentofmicroorganisms,increase thecatalyticsurfacearea,reduceoverpotentials,andsoforth.
1.2EconomicAssessmentofBESMaterials
BothMECandMFCtechnologiesfacesimilareconomicchallengeswhentreating wastewater.Theyworkbetterwithhighstrengthwastewaterandarethereforebetter applicableforindustrialwastestreamswhereCODconcentrationsexceed5gL 1 . Tosomeextent,lowerCODconcentrationscanbecompensatedforbylarger volumes,which,however,alsodriveelectrodecostsasmoreelectrodesurfaceis required.Additionally,apotentialcanbeappliedinMECstoimproveCODremoval rates.Thisisaccomplishedattheexpenseofanodiccorrosion.Anodesaretherefore thebottleneckinMECs.InMFCs,thecostdriveristhecathode.Cathodicoxygen reductionreaction(ORR)arelimitedbyoxygendiffusionandcatalystwear.An excellentreviewonBEScathodesandtheirworkingswaspublishedbyLiuetal. (2014).Asfurtherdetailedinthesectiononcathodes,somepoweroutputsofMFCs usingnanomaterialsreach12Wp m 2 (Wenetal. 2012, 2014)asopposedto hydrogenfuels,whichroutinelyexceed5kWp m 2 (Al-Baghdadi 2005).Forour estimatesweusedatypicalfuelcellvoltageof0.7V.Atthisvoltage,others suggestedthatapoweroutputof10–20Wp m 2 wouldberequiredtooperate MFCsprofitably,butscalingfactorswerenottakenintoaccountandexpensive preciousmetalcathodeswereusedforpreviousevaluations(Sleutelsetal. 2012). Withsuchlowpoweroutput,neithertheuseofpreciousmetalsnormixedmetal oxidecathodesappearstobejustifiedandcheapcarbonshouldbeconsidered, perhapsincombinationwithironormanganeseminerals(Table 1.1).Asinconventionalfuelcells,platinumoncarbon(Pt/C)isoftenusedinMFCsaswell.Duetoits highpowerdensities(forMFCs),frequentlysurpassing2Wp m 2,itisalsocheapona
Table1.1 RankingofMFCcathodenanomaterialsintermsofarealperformance
1EconomicAssessmentofNanomaterialsinBio-ElectricalWaterTreatment5
PinW p m 2 (cathode)Reference
Catalystload inmgcm 2 Chambers
Anode areain cm 2 Cathode support Cathode areain cm 2 Cathode catalyst
CategoryAnode
PreciousmetalCarbonbrushNAC –cloth1Pt/C5Dual2.8Houetal.( 2016 )
CarbonGraphene/ PEDOT 5C –paper12NANADual2.1Wangetal.( 2013b )
5Single2.1Wenetal.( 2012 )
NanocompositeCarbonfelt78GDL10MnO 2 –graphene nanosheet
5Dual2.0Houetal.( 2016 )
NADual1.9Chenetal.( 2012 )
NanocompositeCarbonbrushNAC –cloth1N-doped
graphene/CNT/ Co-Ni
CarbonGraphiteplate5Steelmesh1N-dopedcarbon nano fi bers
GrapheneGraphene –steel3.2C –felt2NANADual1.3Houetal.( 2014 )
GrapheneCarbonfelt10C –paperNAFe/N – functionalized graphene NASingle1.2Lietal.( 2012 )
5Single1.1Wenetal.( 2014 )
CarbonCarbonbrush12.5GDL10N-doped nanosheeton graphene
GrapheneN-doped graphene 1.5C –cloth1.5NANADual1.0Kirubaharanetal. ( 2015 )
2Dual0.8Liuetal.( 2013b )
GrapheneCarboncloth9C –paper9N-doped graphene
PreciousmetalGoethite –steel12.6C –meshNAPt/C0.5Single0.7Pengetal.( 2013b )
PreciousmetalC –cloth7C –cloth7Pt/CNASingle0.5Chengetal.( 2006 )
NADual0.3Zhuangetal. ( 2012 )
NanocompositeC –cloth7C –cloth7CoTMPP0.6Single0.4Chengetal.( 2006 ) GrapheneC –cloth5C –cloth5Bio-modi fi ed graphene
14Single0.2Santoroetal. ( 2013 ) (continued)
CarbonC –cloth20C –cloth1Carbon nano fi bers
Table1.1 (continued)
PinW p m 2 (cathode)Reference
Catalystload inmgcm 2 Chambers
Anode areain cm 2 Cathode support Cathode areain cm 2 Cathode catalyst
CategoryAnode
CarbonRVC97RVC194NANASingle0.2Heetal.( 2005 )
PreciousmetalSingle –walled carboxy –CNT 20C –cloth20.25Pt/C0.5Single0.2Thepsuparungsikul etal.( 2014 )
GrapheneGraphite78.5C –felt1PANI –graphene nanosheets NASingle0.1Renetal.( 2013 )
NanocompositeGraphitegran- ules/felt 16Si –wafer/ nanowires 6MoS 3 NADual0.1Zangetal.( 2014 )
CarbonC –felt197C –felt69Fe/Ca –PANI0.6Single0.04Ledezmaetal. ( 2015 )
PreciousmetalC –felt197C –felt69Pt/CNASingle0.04Ledezmaetal. ( 2015 )
MetalMo –steel1200Steel1200SteelNASingle0.02Dumasetal.( 2007 )
PreciousmetalCNT/Au/TiO 2 9C –paper7Pt –TiO 2 0.5Single1.910 3 Wuetal.( 2013 )
CarbonC –paste0.07C –paste0.07CNT5%Single2.410 4 Reidetal.( 2016 )
NanocompositeC –felt197C –felt74Fe(CO) 5 NASingle2.010 6 Wangetal.( 2013a )
NanocompositeC –paper12C –paper12Pt/C0.5DualNAGhasemietal. ( 2012 )
NanocompositeMagnetite/CNTNANANANANASingleNAParketal.( 2014 )
NanocompositeCNT/TiO 2 on C –cloth 4.5C –brushNANANADualNAWenetal.( 2013 )
CarbonC –cloth16C –clothNANANASingleNALietal.( 2014 )
GrapheneGraphene/ PANIonC –cloth NAC –cloth4NANADualNAHouetal.( 2013 )
PreciousmetalMagnetite –steelNAC –paperNAPt/C0.5SingleNAPengetal.( 2012 ) W p peakpowerinW, NA datanotavailable, PEDOT poly(3,4-ethylenedioxythiophene), GDL gasdiffusionlayer, CNT carbonnanotube, RVC reticulated vitreouscarbon, CoTMPP Co –tetramethylphenylporphyrin, PANI polyaniline
dollarperpowerbasis(~$500Wp 1)comparedtoothermaterials(Houetal. 2016).The runners-upareapotpourricarbonnanofibersandgraphenecomposites.Nitrogenor manganesecanbeusedtoimprovetheirperformance,forexample,N-dopednanofibers cost~$500Wp 1 (Chenetal. 2012)orMnO2-graphenecosts~$2400Wp 1 (Wenetal. 2012).Forgraphene,singlelayermaterial($200g 1)wasusedforourestimatebut otherformsmayfurtherreducecosts.Plainreticulatedvitreouscarbonperformed slightlybetterthangraphenewith$2100Wp 1 (Heetal. 2005).Othertypesof functionalizedgraphenewereN-doped(Wenetal. 2014)orFe/N-dopednanosheets (Lietal. 2012),bothofwhichcost~$4300Wp 1.Therewereseveralextremeoutliers, ordersofmagnitudeaboveorbelowthesevalues.Someofthemusedferricyanideasan electronacceptor.OneworthnotingwasN-dopedgraphenewithonly$3Wp 1 (Hou etal. 2016).AlloftheabovementionedMFCcathodesusecarbonmaterialsascatalyst support.Whilemovingclosertobecomeeconomicallyfeasible,thecostsarestillfar awayfromwhatisnecessarytooperateMFCprofitably.MFCcathodesneedtobelarge, whichisnotonlyanengineeringchallengebutalsodrivesmaterialandalsorealestate costs.
MECs,incontrast,canbeoperatedcompletelywithouttheuseofpreciousmetal catalysts,forexample,withstainlesssteel(Calletal. 2009).Steelisamongthe cheapestmaterials(0.4mmsteelplate,typeA286,~$430m 2;type304~$80m 2) andcanalsoserveasstructuralelementinMECs,furtherreducingcost.As explainedabove,inMECs,anodesarethecriticalcomponent.Escapaetal.(2012) estimatedthatanMECWWTPproducinghydrogengascanbeoperatedeconomicallywhencostsoftheanodecompartmentarebelow$1500m 3 (at2012exchange rates).Thisagreeswellwithourown,independentcalculation(Fig. 1.3),exceptthat weusemethanegasasproductwithascalingcoefficientof0.6(TribeandAlpine 1986).Whilethescalingcoefficientissomewhatarbitrary,existingcommercial
Fig.1.3 Relationship betweenMECreactor capacityandtotalelectrode costincludinganodeand cathode.Errorsarestandard deviationsoffourdifferent tubularreactordesigns. Anodesaregraphite granulesandcathodesare steelpipes
MECWWTParelivingevidenceforthistechnology’seconomicviability.Forour calculationweusedgraphitegranuleanodesintitaniummeshdrumsinsertedinto steelpipecathodeswhichalsoserveasMEChousing.Withtheseassumptions,we foundthatelectrodesmakeup5 2%oftotalreactorcosts.Futurescaling experimentswillshowhowthesecostscontributeinreality.Unfortunately,the datareportedforMECsare,asforMFCs,notstandardized.Patiletal.(2015) suggestedaframeworkforreportingMECperformanceandwereferfutureinvestigatorstothisexcellentarticleinordertostandardizetheirreports.
1.3NanomaterialsUsedBES
1.3.1Carbon-BasedNanomaterials
NanomaterialsinBEScan,asinnonbiologicalapplications,improveelectron transferprocesses(CaiandChen 2004)andcatalyticactivity.Carbonnanoparticles, nanofibers,nanotubes(CNTs),andgraphenearethemostintensivelystudied nanomaterialsinBES.Theirsynthesisisrelativelysimple(Box 1.1)andcarbonas supportmaterialisinexpensiveandwidelyavailable.Itisthereforenotsurprising thatCNTshavebeenusedinBESwherecheapelectricityorgasproductionarethe primarygoals.In Shewanella,oneofthemodelmicrobesinBES,CNTsredirected theelectron flowbetweentheelectrondonorlactateandnitrobenzeneasanelectron acceptor(Yanetal. 2014).Thealteredelectron flowoccurredmostlyoutside Shewanella cellswhereasnitrobenzenehadbeenreducedinsidewithoutCNTs, suggestingthatCNTscanalsoimproveelectron flowbetweencellsandelectrodes. Carbonnanoparticlesalsosupportedhydrogenase-dependenthydrogenoxidationon indiumtinoxide(ITO)electrodes(Szotetal. 2013).TheITOelectrodeswerecoated withcarbonnanoparticles filmswhichwerethenusedtoimmobilizethehydrogenaseenzymes.
Box1.1:PreparationofCarbonNanotubes(CNTs)
Abinitio,CNTsarepreparedbyhightemperaturetechniqueslikearchdischargeandlaserablation.Duetothehighenergyconsumption,thesemethods havebeenreplacedbylowtemperature(<800 C)chemicalvapordeposition (CVD)technique.Nowadays,CVDisthesimplestandmostpopularmeansto growCNTsinthelaboratorysincethealignment,orientation,diameter, nanotubelength,purity,anddensityoftheCNTscanbeaccuratelycontrolled duringsynthesis.TheCVDprocessuseshydrocarbonsasthecarbonsources includingmethane,carbonmonoxide,andacetylene.Catalyticchemicalvapor deposition(CCVD)iscurrentlythestandardtechniqueforthesynthesisof carbonnanotubes. (continued)
Box1.1 (continued)
Procedure:
Allthecatalystmaterialsarecalcinedinairat500 Cfor1h,cooledto roomtemperature,andgroundpriortoCVDgrowth.CNTsaresynthesizedby usingtheexperimentalsetuppresentedinFig. 1.4.Topreparethereaction, 0.1g/10mgofthetemplatemembranewiththecatalyst(Fe,Co,orNi nanoparticles)inporesisplacedinaquartzboatandtheninsertedintothe centerofaquartztube(50mmdiameter,800mmlength),whichismountedin anelectrictubefurnace.Argonispassedoverthecatalystasthereactoris heatedto900 C.Theargon flowisthenchangedforthe flowofareduced carbonaceousgas,e.g.,methane,carbonmonoxide,oracetylene.Forexample, CH4 (99%purity)ispassedattherateof6000cm3 min 1 at1.25barhead pressureforthedesiredreactiontimebetween10and30min.TheCH4 flowis thenswitchedbacktoargon flow,thefurnaceisturnedoffandallowedtocool toroomtemperature.ForlargequantitiesofCNTs,5.0gofcatalystisusedfor areactiontimeofaround30min.
Preparationofgraphene
Generally,singlelayergraphene(SLG)andmultilayergraphene(MLG)are synthesizedbychemicalvapordeposition(CVD)fromacarbonprecursor (carboncontaininggases)oncatalyticmetalsurfaces.Inasurface-mediated CVDprocess,thecarbonprecursor,e.g.,isopropylalcohol(IPA),is decomposedonthemetalsurface,e.g.,CuorNi.Inordertocontrolthe numberofgraphenelayersthatareformed,thesolubilityofthecarbon precursoronthemetalcatalystsurfacehastobeconsidered.Duetothelow solubilityoftheprecursorinCu,SLGcanbeformed.Itisdifficulttogrow SLGonthesurfaceofametalwithahighaffinityfortheprecursor.
Procedure:
Presentedisaneconomical,safe,andsimpletechniquetosynthesizeMLG filmsthroughCVDin30–45mininachemistrylaboratory.Theexperimental setupforthepreparationofgrapheneisshowninFig. 1.5.Nickelfoilis immersedinaceticacidforetchingfollowedbytransferringthefoilintoan airtightquartztubethatwillprotectthesystemfromenvironmentaloxygen andwatervapor.NitrogengasisbubbledthroughIPA,andtheresultingIPA saturatedgasispassedthroughtheclosedsystemwithexhaustwashedina beakerofwaterorgaswashbottle.Thestreampurgesfor5minatarate <50cm3 min 1.Oncethe flameofaMekerburnerreaches575–625 C,itis positionedunderthenickelfoil,thusprovidingsufficientenergyforthe formationofgraphene.The flameisextinguishedafter5–10mintostopthe reactionfollowedbycoolingthesystemfor5min.Theproduct,graphenecoatedNifoilisobtained.
Fig.1.4 ThermalCVDsystemwithatubesystem.FiguretakenfromKozioletal. 2011 with permission
Fig.1.5 ExperimentalCVDapparatususedtosynthesizegrapheneinthelaboratory.Figuretaken fromJacobbergeretal. 2015 withpermission
Grapheneisconsideredsuperiortoothercarbon-basedmaterialssuchasCNTsor graphiteduetoitsrapidchargeexchangerates(Lvetal. 2016),easierintroductionof functionalgroups(Novoselovetal. 2004),easierproductioncomparedwithCNTs (Lvetal. 2013),andhighersurfaceareacomparedwithgraphite(Martin 2009).Like CNTs,graphenecanbedepositedonanumberofsurfaces,suchasnickel(Mink etal. 2013),stainlesssteel(Houetal. 2014),carbon(Houetal. 2013),andsoforth. Thesefeaturesareessentialforanyelectrodebutinparticularforbioelectrodesused inwastewatertreatmentbecausecostisthemostconstrainingfactorinanyutility technologybesidesreliability.However,somereportssuggestthatCNTsmaybe toxictoelectrophilicmicrobesastheyareforsomeeukaryoticcells(Flahautetal. 2006;Martin 2009).Graphene-basedmaterialsappeartohaveabiocidaleffecton microbialbiofilmgrowthaswell(ElMekawyetal. 2017).Thebiocidaleffectof graphenethuslimitstheapplicationofgraphenetocathodicoxygenreduction reactions(Liuetal. 2013b;Renetal. 2013)ormembranes(Perreaultetal. 2014;
Zhaoetal. 2014)wherethisveryeffectisevendesired.Despitethebiocidaleffect, CNTsandgraphenecompositescanalsobeusedasanodematerial,forexample,as polymercomposites(Wangetal. 2013b),dopedforimprovedcatalyticactivity (Quetal. 2010;Limingetal. 2014;Kirubaharanetal. 2015;Yangetal. 2015a; Houetal. 2016)ordepositedonmetal(Houetal. 2014)aswellascarbon(Houetal. 2013).ExcellentreviewsforgrapheneinMFCapplicationswererecentlyprovided byElMekawyetal.(2017)andforCNTsbyYazdietal.(2016).
1.3.2MetalandMetalCompositeMaterials
Metalsandmetalcompositenanomaterialsmakegoodelectrodesforenzymeand wholecellattachmentandhavebeenwidelyusedasanodeaswellascathode materialsthroughoutthelastfourdecades(Turneretal. 1983;WilsonandTurner 1992;Xiaoetal. 2003;Xuetal. 2014).Advantagesofmetalsaretheirlow resistance,affinitytobiologicalmaterial,highstructuralstability,lowprices,and highcatalyticactivities.Thelattertwoadvantagesdonotalwaysapply.Forexample, titaniumhasalowercatalyticactivitycomparedwithplatinumwhereasplatinumis moreexpensive.Stainlesssteelisagoodcompromiseinmanycasesbecauseitis cheapandcatalyticallymodestlyactive.Ithasbeenusedforcathodes(Calletal. 2009;Selemboetal. 2009)aswellasforanodes(Dumasetal. 2007, 2008;Houetal. 2014;Ledezmaetal. 2015;Pengetal. 2016).However,nano-steelhasnotbeenused sofarandsteelwasmostlyusedasstructuralsupportforothernanomaterialsin compositeelectrodes,forexample,assupportfornanofibersincathodes(Chenetal. 2012).Asananode,stainlesssteelhasthetendencytocorrode,whichmakesita poorsupportmaterialincompositeelectrodes(Ledezmaetal. 2015).Likesteel, nickelservedasstructuralsupport,forexample,withgraphenecoatingasahydrogen-oramethane-producingcathode(Caietal. 2016).Nonetheless,nickelisan inexpensivehydrogencatalystitselfanditsperformanceiscomparabletosome platinumnanoparticleformulations(Selemboetal. 2010).Itisthereforeplausibleto usenickelnanowiresforhydrogen-producingcathodesaswell(Nieetal. 2013). Unfortunately,nickel-basedelectrodeshavethetendencytodissolveintheelectrolyteovertime(Selemboetal. 2010;Siegertetal. 2014)anditisforthisreasonthat preciousmetalelectrodeswillstillplayaroleinBESapplications.Toreducecost, metalcompositeswithpreciousmetalsseemaviableapproach.Gold/titanium dioxideCNTswereusedoncarbonpaperanodes(Wuetal. 2013).However,the performanceof2.10 3 Wp m 2 waswellbelowthatobservedinotherMFCs.
1.3.3Minerals
Despitetheirinstability(Kalska-Szostkoetal. 2013),ironnanomaterialsareconsideredpromisingalternativestopreciousmetalsduetothelowcostsofironoresand
theirvirtuallyglobalavailability.Ironmineralparticlesarewellknowntoimprove turnoverratesinmethanogenicmicrobialcommunities(Siegertetal. 2011;Cruz Viggietal. 2014;Yamadaetal. 2015;Yangetal. 2015b).Magnetitenanoparticles wereshowntocompensateforlackofpiliin Geobacter (Liuetal. 2015),whichhave beenpostulatedtoaccelerateinterspecieselectrontransferinmethanogeniccommunities(Moritaetal. 2011;Rotaruetal. 2013).Moreover,electrophilicmicrobessuch as Geobacter haveagreataffinitytoironminerals,suchasmagnetiteandpyrite (Regueraetal. 2005, 2007).ThisfeaturemakesironmineralnanoparticlesinterestingforBESwastewatertreatment.WhilemagnetitenanoparticleshavebeeninvestigatedinMFCsbefore(Pengetal. 2013a),pyritenanowiresweresynthesizedbut nevertestedinBES(Cabán-Acevedoetal. 2012).Sincethereisevidencethatnanopyritesandmagnetiteplayaroleaselectronshuttlesintheenvironment(Hellige etal. 2012;KatoandIgarashi 2018),theseinexpensiveironnanostructureswill receivemoreattentioninfuture.Othersulfidesofinterestare,forexample,molybdenumsulfidesastheyhavebeenreportedtobeefficienthydrogenproducers (TokashandLogan 2011).AninterestingapproachisthecombinationofMoS3 withsiliconnanowiresinhydrogenphotocatalysisalongwithanodicwastedegradation(Zangetal. 2014).
1.3.4Anodes
Bio-anodesusuallycomewithnanomaterialsincluded.Theyarecalledmicrobial nanowiresandareassociatedwithimprovedattachmentaswellaselectrontransport betweencellsandelectrodes(Regueraetal. 2005, 2007;Strycharz-Glavenetal. 2011; Rotaruetal. 2013).However,humannatureistofurtherimprovenaturalsystems,and hencethereisaplethoraofnano-modificationsofbio-anodes(Sonawaneetal. 2017). Despitetheirbiocidaleffect,CNTswereoftenusedtoimproveanodeperformance.In MFCwastewatertreatment,theyprovedvaluableanodeupgradesforexample,when multi-walledCNTswereused(Thepsuparungsikuletal. 2014).Theintroductionof oxygenfunctionalgroupsfurtherimprovedCNTanodeperformanceasitwas reported,forexample,forcarboncloth(Lietal. 2014).Electrospunnano fibershave beenusedasanodematerialwith Shewanella asanelectrocatalyst(Patiletal. 2013). Currentgenerationwastenfoldhigherthanwithoutnano fibers,aresultwhichhad beenattributedtotheincreasedsurfaceareaofcarbonnano fibers.Anothergreat advantageofcarbon-basedanodesinBESis,besidetheirlowpricesandtheaffinityof microbestocarbon,theircorrosionresistance.Unfortunately,carbon-basedmaterials havelittlecatalyticactivitywhichisnotdesiredforsomeapplications,forexample,in wateroxidizinganodes.Traditionally,preciousmetalswereusedinsuchcaseson carbonortitaniumsupports.Inclassichydrogenfuelcells,preciousmetalsarestillthe mostpotentandeconomiccatalystswhenthedollarisusedasreferenceforpower density.Forexample,somecommercialmixedmetalanodeshaveamarketpriceof~ $30Wp 1)whereasa10%platinumoncarbonelectrodecosts~$0.03Wp 1).One possiblewaytofurtherreducecostsofpreciousmetalelectrodesistoincreasetheir
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one thing is still needed, and that is money It is for the French Government to ask for it, and for the French Parliament to grant it. Certain there be who deliberately oppose French colonial expansion; with them discussion is impossible. I do not try to convince them, for they are already proved to be in the wrong.
There are, however, others, noble and loyal Frenchmen, who stigmatize as sterile all the efforts we make beyond seas to add to the possessions of our native country. “What,” they urge, “you talk of wholesale emigration, when the population of France is by no means increasing!”
This is, after all, only a specious argument. Who speaks of advising expatriation en masse to Frenchmen for the sake of peopling distant countries? All the colonies suitable for peopling have already been appropriated by our English rivals. Australia was the last of them.
With regard, however, to colonies for exploration, it is quite a different matter. And with the fullest conviction of my soul, I say France ought to acquire such colonies. Through them alone will she recover her commercial ascendency, which has been so seriously jeopardized; through them alone will her social position become assured
Take, for instance, some child, the son of a workman or farmer: he goes to the school of his quarter or village. Intelligent and hardworking, he soon wins the affection of his teacher. “Work,” says that teacher; “to every one the reward is sure, according to his merits. Think of Pasteur, the son of a workman, to whom all Europe renders homage.”
Believing what he is told, the child works on. At first the State fulfils the promises made through the lips of the master. The teacher has spoken to the inspector of his protégé, the rector bestirs himself in the matter, the minister even intervenes, encouragement and money aid alike are lavished upon the young fellow. His zeal increases, he redoubles his application, he passes all the examinations and gets all the honours possible, till the University has
no more to teach. Teacher, rector, minister, all justly pride themselves in having done their duty by him.
MEDAL OF THE FRENCH SOCIETY FOR THE ADVANCEMENT OF SCIENCE.
Then the son of the workman begins his life in the world.
Oh, how changed is everything to him now! Knowledge and industry are much, it is true, but there are still two applicants for every post, for every social function, and it is always the weaker, the less skilful, or rather perhaps the less fortunate, who goes to the wall.
The State has no other situation to offer him, and there is a regular glut of brain-workers already in commerce and in manufacture. Still it is necessary to eat to live.
It is easy to say “go back to the workshop or the plough,” but it is against human nature to do so; the cultivated brain, the matured intelligence, need the intellectual food to which they have become accustomed. The hands are too soft and delicate now for manual labour, nor are the muscles strong enough for it.
One more embittered, discontented, unfortunate man has been produced, that is all, and who knows but that to-morrow he may astonish the world by some attempted crime or act of folly, the result of his despair, perhaps even of actual hunger?
Am I making excuses for an anarchist? By no means. I have but proved the necessity of French colonial expansion in colonies of exploration.
If we wish to turn our distant possessions to account, the criminal of yesterday, the dangerous member of society, might go there, and in directing industrial or commercial enterprises find legitimate employment and a fair return for all his intelligent efforts and for the work and study of his youth.
There is plenty of labour to be obtained out there, for it is only the natives, of whatever tribe or colour, whose temperament is hostile to manual work.
More than that, these very natives who are now in a degraded state of barbarism, if taught by intelligent Europeans, would soon rise above their present condition to more of an equality with their instructors. Not only would the young man of whom I have been speaking live a happy life; not only would he win riches for himself and add to the wealth of his native country, but he would also aid in bringing about what, in my opinion, is the noblest of all possible ambitions, the amelioration of the lot of his fellow-creatures, for to make them better and happier is to share in the work of God Himself.
So logical is this reasoning, that my only wonder is why those who have the good of humanity at heart have not thought of it before myself.
Is not our French Sudan just such a fertile colony as is well suited for playing a part in what I may call the future social policy of France? I can answer that question in a very few words.
MEDAL OF THE ‘SOCIETÉ D’ALLIANCE FRANÇAISE.’
I have visited the lower course of the river, with the districts under the control of the Royal Niger Company, and I can confidently assert that except for palm-oil, which is only to be obtained on the seaboard, none of the exports, gum, india-rubber, ivory, and above all, karité, are wanting in the French Sudan. In fact, we have all these things in greater quantities than the English, without counting the products peculiar to our districts, but unknown at the mouth of the river.
Let us then make that railway, and make it quickly. Do not let us waste any more time talking about it; do not let us turn aside for any other projects, and when some 373 miles of iron road unite some 622 miles of the navigable Senegal, with no less than 1056 miles of the Niger, all alike fit to be navigated by our boats, we shall have a second Algeria, larger and richer than the first. The mind can scarcely grasp the idea of the new source of fortune to be opened to France by a thing so simple as this, a thing in which the Belgians have been beforehand with us—the construction of a railway. Stanley was right when he said Africa would belong to the first who should lay down a line of railway through it.[12]
This will bring us to Ansongo. Are we to let it be the limit of our zone of trading operations? No, certainly not; and this brings me to a second result won by our expedition: the opening of relations with the Awellimiden.
I have constituted myself the defender of the Tuaregs. I have shown them to be less cruel, less traitorous, less hostile to progress than they are generally said to be. It is for the reader to judge whether the adventures I have related do or do not prove my impressions to have been correct.
One thing, however, I must stipulate, and that is: if we let months or years slip by without improving the relations opened with the Tuaregs of the Niger by further contact with them, we shall find them more difficult to deal with, more suspicious, altogether less accessible than we did during our stay in their country.
As I have already said, the Azgueurs were in our hands after the journey of Duveyrier. Ikhenukhen, their great chief, who was honoured and obeyed by them, was our friend. When the treaty of Rhâdames was made, we said to them, “We want to go to the Sudan by way of Aïr: you will guide us, you will protect our traders, you will hire your camels to us, and you will find it to your profit to do so.”
A Tuareg proverb says, “You should never promise more than half what you mean to perform.”
The Azgueurs of course expected our caravans to arrive, and they are still expecting them. Gradually, however, they are beginning to doubt us. “What,” they are saying, “did those Frenchmen, who seemed so anxious to trade in our country, come to do here?” When this question is put to a Tuareg, he will answer immediately, “They came to spy; they were the spies of a great army, which will come to take away our liberty and our independence.”
MEDAL OF THE LYONS GEOGRAPHICAL SOCIETY
In the English of Tripoli and their agent, the Kaimakhan of Rhâdames, they would have advisers, who would increase their suspicions of us. Little by little the sympathy the Tuaregs had felt for us would give way to dread of us. Ikhenukhen is dead now, the Sahara is closed to us, more completely closed than when Duveyrier visited it, or when Barth and Richardson crossed it.
If we are equally negligent with the Awellimiden, we shall obtain equally melancholy results.
If only an opposite policy could be pursued, how different everything would be!
Whilst waiting for that iron road, and alas! its completion is very far off! the only means of transit—bearing in mind the impossibility of navigating the second section of the river—is to employ the comparatively cheap and easily obtained ships of the desert, the ugly but useful camels.
Now the camels all belong to the Tuaregs, generally to their Imrad tribes.
Let us imagine that the railway is completed, that boats brought up in sections to Kolikoro have been put together there, and are going down the river as far as Gao, boats sufficiently well armed to make the French respected, and of sufficient tonnage to carry merchandise; we should at once have either at Gao or somewhere
else in its neighbourhood, a centre, so to speak, of transit, to which the Tuaregs could bring their animals to be laden, and acting as convoys to our caravans, would be most useful auxiliaries to the French traders.
Do not let any one urge against this the pillaging instincts of the Tuaregs. To begin with, it is in our power, if necessary, to destroy, or at least to insist, upon the removal elsewhere, of the riveraine negro villages, an excellent way of keeping the natives in awe, for we should then have it in our power to avenge ourselves efficaciously on them in case of their hostility, for it is from these riveraine districts that they obtain the grain which is their only food.
I assert, however, that it would never be necessary to proceed to such extremities as that.
The Tuaregs are alike too intelligent and avaricious of gain to risk raids, the result of which would be uncertain, when merely letting out their camels on hire would bring them in alike a greater and a surer profit.
By doing as I suggest, the old route from Gao to Lake Tchad, one of the most ancient in Northern Africa, could be reopened. This route, bearing as it does in the direction of Gober and Aïr, and skirting the Sahara, as it were in the rear, might in the end be made to connect the French Sudan with Algeria and Tunis.
To achieve this I repeat we must not give the marabouts, who are badly disposed towards the French, time to destroy our work before it is fairly begun; we must not by too long a delay, awake once more the suspicions of the Awellimiden, which are always easily aroused.
I do not pretend to say that any immediate profits would result from the course I advocate. Skins, wool, and gum are all too heavy to make it worth while to export them by difficult and costly modes of transport from Timbuktu to Kolikoro, and from Kolikoro to Diubeba, where ends at the present moment the railway from the Senegal to the Niger.
MEDAL OF THE MARSEILLES GEOGRAPHICAL SOCIETY.
It is, however, absolutely necessary to pave the way for traffic even at the cost of a temporary loss, so that it may be in full swing from the very day of the completion of the railway, when steamers will begin to ply on the navigable portion of the Niger.
On that day our hydrographical map, which is so far the chief result of our expedition, will find its use!
Was our stay at Say a profitable one? The future alone can decide.
I do think, however, that at least our gentle and benevolent behaviour to the peaceable natives, to the tillers of the soil, the Koyraberos, must, however obtuse their intelligence, have proved to them that these French infidels, these Kaffirs, as they called us, were not really exactly what their marabouts told them we were: ferocious beasts.
Moreover, our establishing ourselves in our island, and our stay at Fort Archinard, in spite of the prohibition of our enemy, Amadu Cheiku, under his very eyes, as it were, and in spite of all his satellites could do, all his vain intrigues against us, must surely have weakened his influence and his prestige.
We could not possibly have done more than we did with the very small force at our command, and in view of the instructions we had received to maintain the pacific character of our expedition,
instructions, alas! which to the end remained incomplete, and were very different from what I had hoped they would be.
With regard to the Lower Niger it is best to be silent. There is far too much competition there with other European nations, and it would only lessen the effect of the results we had been able to obtain, whether those results were great or small, to publish what they were. It is for diplomacy to deal with them, bearing in mind that our rivals know on occasion how to act with what I may call quite a special bad geographical faith, which is not, however, any longer effective, since we have now reconnoitred and examined the districts in dispute.
I may add that we also brought back with us a few collections, and what was, as it appears to me, a most important point, the results of as careful a study as possible of the different dialects spoken in the river districts.
There is nothing which gains the confidence of the natives more than to be able to speak, or even to jabber, their language. The effect on the Tuaregs especially is immense when they find that a European can say a few phrases in Tamschenk, and a very great stride has been made towards a good understanding when those sentences have been pronounced.
MEDAL OF THE CHER GEOGRAPHICAL SOCIETY.
Whatever may be the results of our journey, I should be guilty of the grossest ingratitude if I concluded my account of our adventures in any other way than by thanking all the devoted companions who helped me to bring it to a successful conclusion.
Our negroes, those brave Senagalese, whom we have watched at their work so long, who were so devoted, so French, who so blindly followed the chief whose service they had entered, had held their own lives cheap, and now shared with us the proud sense of duty accomplished.
Then above all, our thanks are due to my friends Baudry, Bluzet, Taburet, and Father Hacquart. We were going back now to civilized life, perhaps to disperse to the four corners of the earth, but a bond had been formed between us which nothing will ever break. As for me, that bond was made up chiefly of loving gratitude, for to them is due the fact that I was able to keep my oath made when Davoust died, to serve my country and to increase the extent of the future possessions of France.
NATIVES OF SANSAN HAUSSA
Thanks too must be given to those who aided me by their influence, their encouragement, and their contributions, no matter how small. As my readers have seen, the beginning of the hydrographical expedition I commanded was set about with many difficulties, and I can honestly assert that I suffered far more personally just because of my zeal for the task I had undertaken; a task which when completed would extend the area of our colonial possessions and make them better known, which would add to the wealth and the power of my native country. Yes, I suffered more than if I had been a bad officer, caring little about his duty.
I wish I could say that at least all was changed on my return, but truth compels me to add that there were certain notable exceptions to the general sympathy with me, and the general kindness of the reception given to me.
GRAND MEDAL OF THE PARIS SOCIETY OF COMMERCIAL GEOGRAPHY.
But never mind, the sense of having done one’s duty is worth more than anything else.
It is to you, dear friends, dear companions on the Niger, that I add —“Let people say what they will; a hundred years hence many things and many men will be forgotten, but for all that, it will be as true then as it is now, that our hydrographical expedition was the first to descend the Niger, the first to explore its course from Kolikoro to the sea.”
A French sailor, Francis Garnier by name, on his way to Tonquin, which he had to aid in conquering, and where he was to end his days, wrote to his mother describing all the difficulties he would have to contend with, adding, “But I do not mind, mother dear. Forward, for the sake of old France!”
For ourselves, and for those who are to come after us in Africa or elsewhere, I too close my narrative with the same words. “Forward, for the sake of old France!”
THE C N from T to B .
Reduced from the Original Surveys made by the H Expedition.
(Large-size)
INDEX
A K , Arab name of Hourst, 90, 191, 196, 309
Abder Rhaman, a chief, 142, 144
Abdu, 285-288, 293
Abdul Dori, 65, 66, 78, 98
Abdulaye, a carpenter, 96, 189, 287, 319, 320, 335, 364, 370, 399, 496
Abdulaye Dem, Tierno, 41, 70, 84, 95, 96, 157, 196, 286, 338, 352, 353, 367, 397, 416
Abdul Bubakar, 329
Abdul Kerim, 88-90, 101, 103, 124, 146, 153, 154, 168, 174, 184, 191
Abegga, 484, 485
Abiddin, 75, 81, 101-108, 114, 118, 120, 121, 135, 140, 141
Abo, 350, 488, 490, 491
Abu, 147
Achur, 125
Adria, 158
Agata, a village, 135, 136
Aghades, 352
Agibu, 373
Agony, 358
Agoult, Naval Lieutenant, 456, 487, 491
Ahmadu Mumi, 280, 386, 387, 389
Ahmady Mody, 318, 338
Air, 176, 202, 207, 243, 247, 505, 507
Ajacin, 443
Akassa, 452, 488, 493
Algeria, 49, 129, 144, 201, 228, 242, 247, 504, 507
Algiers, 228
Ali, 306
Aliburi, 282, 310, 313, 320, 388
Alif, 118
Alimsar, 240, 241, 426
Alkori, 204
Al Walidj, 104
Amacher, 202, 222
Amadi, 79, 80
Amadu, a guide, 436-439, 442-445, 456, 457, 468
Amadu Cheiku, 37, 181, 271, 274, 280, 283, 290, 291, 307, 312-317, 372, 384, 508
Amadu Lobbo Cissé, a chief, 78
Amadu Saturu or Modibo, 285, 286, 288, 290-292, 299, 326, 347, 359, 361, 365-368, 373, 378, 382-387, 388-391
Amiru of Torodi, 313
Amrar, 178, 244
Ansars, 208
Ansel Makkoren, 144
Ansongo, 99, 100, 165, 181-184, 188, 192, 269, 368, 369, 373, 498, 499, 504
Arabu, 310, 364
Archinard, General, 37, 284, 298, 299, 500
Ardent, The, 452, 492
Ardos of Massina, 316
Argungu, 412, 421
Arhlal, 101
Armas, the, or Romas, 144, 168, 208, 209, 216, 217
Aron, Lieutenant, 491, 492, 494
Askia, 165, 167, 193, 207, 316
Assaba, 487-490
Atakor n’Ahaggar, 202, 207, 243
Atchino, 331, 358, 399
Attanoux, 84, 160, 172
Aube, 30, 495
Aube, The, 52, 59, 60, 94, 99, 123, 146, 147, 156, 186, 188, 193, 251, 255, 256, 258, 260, 275-277, 299, 304, 338, 357, 358, 459, 463, 467-469, 494
Auru, 265, 368, 369, 438, 449, 464, 466, 467, 470, 472, 474, 479, 485
Aussa, Igwadaren, the, 90, 131
Autel Makhoren, 134
Awellimiden, the, 88, 104-106, 120, 129-131, 136, 148, 152, 167, 170, 173, 174, 176, 177, 181, 195, 196, 201, 203, 204, 209, 217, 219, 231, 236, 238, 240, 241, 243, 246, 247, 271, 315, 379, 426, 504, 506, 507
Azemay, 277
Azgueurs, the, 160, 172, 197, 201, 248, 504
Baba Hamet, 80, 146, 177
Badjibo or Guadjibo, 470
Bafing, a stream, 7, 42
Bafulabé, 7, 34, 38, 42
Bakel, 27, 30
Bakhoy, the, 7, 39, 42
Balia, 180, 181
Ballot, Governor, 33
Bamako, 52, 289, 405
Bamana Dankun, 71
Bamba, 136, 148
Bambara, 60, 62, 68, 71, 281, 351, 411
Bandiagara, 65, 288, 290, 363, 364, 367, 371, 372
Bargu, The, 475, 477
Baror, a rock, 149, 155
Barth, Dr. Henry, 1, 2, 10, 75, 88, 89, 101, 124, 129, 142, 149, 152, 156, 165, 166, 179, 180, 184-186, 194, 201, 240, 251, 357, 367, 484, 485, 505
Baruba, 142
Baud, 32, 33, 285, 286, 423, 427
Baudry, Lieutenant, 14, 17, 20, 21, 23, 28, 32, 34, 36-39, 41, 64, 94, 97, 100, 132, 160, 182, 188, 197, 254-257, 261, 302, 323, 335, 337, 352, 353, 364, 371, 399, 421, 468, 469, 485, 498, 510
Baye Hamet, 80, 146, 177
Beba, 182
Bechir Uld Mbirikat, 88, 118
Beckay Uld Ama Lamine, 75, 76
Bedda of Ida, 228
Belle or Bellates, 215, 216, 251
Benin, 493
Beni-Omia, law of, 236-238
Bentia, the Biting of Barth, 194
Benuë, 479, 481, 483
Berber, 203, 204
Bidda, 437, 476, 488
Bikini, 405
Bilali Cumba, a coolie, 29
Bilinga, 375
Bina, Ali, 47
Biskra, 78
Bluzet, Lieutenant, 37-41, 44, 45, 64, 94, 97, 100, 158, 290, 303, 304, 325, 340, 353, 354, 374, 408, 469, 510
Bobo, 282
Bokar Ahmidu Collado, 372
Boker Wandieïdu, 218, 252, 269-271
Bolard, Léon, 19, 20, 38
Bonnier, Colonel, 30, 118, 218
Bori, 100
Bornu, 179
Bozos, the, 316, 351, 354
Brass, 488, 493
Brazil, The, 21, 23
Brid’oison, M , 352
Brière de l’Isle, 24
Brière de l’Isle, The, 27, 30
Bubakar-Singo, 28, 39
Bubodji, 406
Burdane, 202
Buré, an island, 189, 191
Burgu, 408, 420, 423, 455
Burrem, 98, 100
Burrum, 10, 160, 165, 413
Bussa, 5, 289, 303, 408, 425, 431, 433, 434, 437, 439, 440, 443-449, 451, 452, 454, 459, 462, 470, 472, 474, 479, 481, 498, 499
Bussuma, 373
Caillé, René, 75
Cape Verd, 21
Carnot, M , 176
Caron, 8, 33, 41, 309
Carrol, Captain, 473, 475, 476, 486, 487, 490
Cayor, 23, 24, 282, 319, 364, 388
Chalor, a rock, 149
Chambas, the, 204, 248
Charenton, 435
Chaudié, M., Governor-General, 37, 496
Chautemps, M , Colonial Minister, 37
Cheibatan, the, 240, 242
Cherbourg, 22
Colbert, 5
Congo, the, 36
Conquet, 399
Dafins, the, 274
Dahomey, 32, 33, 96, 289, 290, 331, 358, 399, 474, 496
Dakar, 21, 25, 87
Damels, 23
Dantec, The, 52, 95, 99, 156, 188, 254-256, 260, 357, 463, 465, 468, 469, 492, 494
Davoust, Naval Lieutenant, 7, 10, 34, 427, 439, 495, 510
Davoust, The, 11, 13, 21, 23, 28, 29, 34, 38, 41, 44, 59, 60, 65, 93, 99, 112, 117, 146, 149, 156, 178, 193, 194, 250, 255, 256, 259, 263, 277, 300, 306, 370, 459, 465, 469, 494, 495
Day, 93
Dē, 367
Debo, Lake, 74, 78, 140, 298, 334, 405
De Brazza, 482
Decœur, 32, 33, 286, 358, 423, 436
Delcassé, M., 6, 7, 10
Dendi, 317, 377, 404, 406, 409, 411, 413, 414, 417, 419, 423, 446
Dendikobes, the, 377
Dentchendu, 385, 391, 421
Dergona, 179, 180, 181
Desa, 268
Desbordes, 500
Destenaves, Captain, 34, 39, 65, 66
Diafara, 373
Diamu, 97, 337
Diena, 35
Digui or Samba Amadi, 39, 41, 95, 197, 255, 256, 259-261, 264, 267, 275, 317, 318, 329, 369, 376, 381, 399, 407, 442, 454, 459, 460, 462, 463, 465, 467, 486, 496
Diko, 153
Diubeba, 42, 507
Diulas, the, 330
Djamarata, 368, 379
Djanaru, 316
Djerma, 385-389, 421
Djermakoy, 384, 385, 421
Djermankobes, 298, 313, 325
Djidjima, 442
Djitafe, 81
Djula, 375
Dodds, General, 358
Dongoe, 148, 149, 218
Dori, 65, 66, 243, 312, 368, 373
Dosso, 389
Drew, Mr., 474, 475, 481, 485, 486, 490
Duentza, 312
Dunga, 280-284, 300, 312, 382, 387, 397
Dungu, 313, 315
Duveyrier, 197, 201, 243-245, 248, 504, 505
Ebener, Colonel, 33
Eguedeche, 145, 146
El Abaker, 208
El Hadj Omar, 75, 76, 79, 129, 313, 314, 316, 386, 397
El Khotab, 154, 168, 170, 240
El Mekki, 182, 183, 186, 270, 271
El Sirat, 272
El Waghdu, 124
El Yacin, 178, 219
Emir el Munemin, 308, 314
