Chapter1
EnhancedPhotocatalyticActivitybyUsing ModificationActivatedCarbon
SamiraBagheriandNurhidayatullailiMuhdJulkapli
1.1Introduction:BasicPrinciplesofHeterogeneous PhotocatalysisSystem
Thepublishedarticleshavespecifiedthebackgroundintheoryandenvironmental supplicationinheterogeneousphotocatalysissystemforsemiconductors.
Oneofthemainlimitationsofutilizingsemiconductorsisthepowernecessity duetotheultravioletlightusage(Huangetal. 2014),althoughupgradingthephotocatalyticsystemsmayelevatethereactionrateandhenceforwardreducethetime ofresidenceandminimalizeenergyconsumptionperunitofvolumebeingtreated. Thismightbeaccomplishedbythephotocatalysismaterialdepositiononhighsurface areamaterials,whichwillparticularlyabsorbthepollutedmoleculesandwillfixate themaroundthephotocatalysisparticle.Theselimitationshavehelpedresearchers tofindanyworthyinitiativeofsemiconductorfortheoperationofsomeparticular pollutants,ortrytoformulatelatesttechniquesofdeposition.ThepHofthesolution,thesupport,andthekindofpollutantplaysasignificantroleintheexploitof photocatalyticprocess.
Manyeffortshavedeclaredtheusageofactivatedcarbonasacatalystsupport forthesemiconductorbutithasbeenalertedthateffectiveabsorptionofpollutants intotheabsorbentareamayhinderdiffusiontothecatalystandthusmayaffectthe entireprocess(Quiñonesetal. 2014).Theemploymentofactivatedcarbonlikea braceforthetitaniumoxide(titania)turnsouttogivegreatertremendousabovethe othermediums,duetoitspotentialtoabsorbpollutants,also,itshighabsorption capabilityduetoitshighsurfaceareaanddecentporosity.Asspecified,medium poresofactivatedcarbonwilleasethediffusionofpollutantsandproductdischarging
S.Bagheri(B) · N.MuhdJulkapli
NanotechnologyandCatalysisResearchCentre,UniversityofMalaya,KualaLumpur,Malaysia
e-mail:samira_bagheri@um.edu.my
N.MuhdJulkapli
e-mail:nurhidayatullaili@um.edu.my
©SpringerInternationalPublishingAG,partofSpringerNature2018
S.BagheriandN.MuhdJulkapli, NanocatalystsinEnvironmentalApplications, GreenEnergyandTechnology,https://doi.org/10.1007/978-3-319-69557-0_1
2S.BagheriandN.MuhdJulkapli fromthesurface.Additionally,thehighabilityofactivatedcarbontoabsorbfluids mayreducethepenetrationofultravioletlightsintosmallareas,anditmaycause confiningofpollutantswithintheporeswithoutgettingabletodiffuseintotheouter surfaceforfurtherreactionwiththepollutantsOHradical.Furthermore,somekinds ofpollutant,suchasphenol,maystartpolymerizationontheAC’ssurface,which cancauseunchangeableabsorption.
1.2ActivatedCarbon
1.2.1CharacterizationofCarbonNanomaterials
Lately,carbonnanomaterialstechnologyhasmadeunexpecteddevelopmentdueto itsvarietyofphysicochemicalproperties,suchasexcitingelectronicproperties,electricalconductivity,tunableporosity,lightweight,chemicalandthermalbalancing, andthepotentialtoacquireanimmenserangeofmorphologies(Poonjarernsilpetal. 2014).Henceforth,carbonmaterialshavefoundalargenumberofapplicationsin differentdomains,varyingfromenvironmentalscience,absorbent,drugdelivery, catalyst,electrodematerials,stationaryphaseinthechromatographysystem,energy storage,andmanyothers.However,forsomeparticularapplications,functionalizationisessentialatcontrollablesizeandshape.Nevertheless,theproductionof suchmaterialsusuallyrequiresveryharshconditionsandhasseverallimitssuchas extremetemperatureofthecarbonizationprocessinthefirststepupto(>800°C) andfollowedbychemicalorphysicalactivationtotransformcarbonmaterialsinto activatedcarbon.Furthermore,itissignificantlyimportantheretoexploreeconomicalandsustainablewaystogetcarbonmaterialsfromrawmaterialsotherthancrude oilornaturalgasleadtoare-explorationofthisfield
1.2.2TransformationofBiomasstoCarbon
Biomassconversiontocarbonmaterialsthroughcatalyticapproachnormallybegins withhydrolysisofdehydrationandcellulosechainsanddividedintomonomer’s solubleproductsthatcomefromthehydrolysisofcellulose,condensationorpolymerizationofthesolubleproducts,aromatizationofthepolymershenceformed,and growthofthenucleisocreatedbylinkageanddiffusionofspeciesfromthesolution tothenucleussurfaceandfinallyappearanceofshortburstofnucleation.
1.2.3CatalyticTransformationofBiomasstoCarbon
Greenchemistry,nowadays,isbecomingmoreandmoreconnectedwiththecatalytic processonbiomassconversiontocarbonmaterials.
1.2.3.1HomogeneousCatalyst
Thesolventsofcatalystasionicliquidshavereceivedenoughattentionbecauseofits lowvaporpressure,stability,andrecyclability(Liuetal. 2013).Thekindsofnovel greensolventareionicliquidswiththerelativelylessmeltingpointandappearas acrystalingeneralconditions.Celluloseisbalancedviainter-andintramolecular bondsofhydrogen,sothatrigidbundlescouldbecreated,whichmakesitdifficult tosolubilizewithcommonorganicsolventsandwater.Ionicliquidshavesignificant roles;itactsbothasasofttemplatetoformulatethecharacterizedporestructuring forthedevelopmentofahierarchicalporouscarbonstructureandasacatalystwhich resultsinenhancedionthermalcarbonyields(Weietal. 2011).Thus,ithasbeen demonstratedthatinthepresenceofanacidcatalyst,theutilizationofionicliquids canembracetheefficiencyofthehydrolysisofglucosecellulose(Yangetal. 2012).
1.2.3.2HeterogeneousCatalyst
Theutilizationofheterogeneouscatalysisalongwithanimmenserangeofdesigns islessexpensiveandextraordinarilystableathightemperature.Thismethodhasthe benefitofbeingveryeconomicalandmildifwefollowsomerulesofgreenchemistrysinceitdoesnotaddorganicsolventwithresultingcarbon,whichisspherically shapedandthesurfaceisdecoratedwithoxygenatedfunctionalgroups(Sevillaand Fuertes 2009).Thismethodalsoinvolvessimplereactionmechanismsforthecreationofcarbon,whichinvolvesthedehydrationofcarbohydrateintoafuranlike molecules,mainly5-(hydroxymethyl)-2-furaldehydeasaninitialstepandfurther polymerizationandcarbonizationasanextstep.Thisreactionpossessesahigh potentialforthecatalyticimprovementbiomasssince–C–C–couplingtakesplace withconsistentoxygenremoval(thereactioninvolvesthedispatchmentofCO2 and water)fromcarboxylicacids,thelatterofwhicharemutualintermediatesintheprocessofbiomassconversion.Ifwecomparehomogeneouscatalysis,carbonmaterials obtainedthroughaheterogeneouscatalyticprocessconsistofanaromaticcorecontainingpolyfurane-typeunitswhichissurroundedbyoxygen-richpolarfunctional groupssuchasCOOH,–OH,–C–,and–O–,makethematerialsmorehydroscopic andhydrophilic,andhavealesserdegreeofgraphitization.
Nevertheless,theeffectiveexploitationofcelluloseisamainchallengeinheterogeneouscatalysisapplication,sincecelluloseitselfhasatough,mainlycrystalline,chemicallystableandwaterinsolublecharacteristics,whichareinducedfrom theintra–intermolecularhydrogenbonds.Themostcommonlyusedheterogeneous
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catalysesfortheconversionofbiomassarealkalisalts,metals(Ni,Rh,PT,Ru,Pd,Ir, andAg),metaloxides(CeO2 ,ZrO3 titania,andAl2 O3 )usuallyonsupports,andmetal oxidecatalystsatmediumtemperatures(300–425°C)whichinvolvesdeoxygenation reactioncombinedwith–C–C–couplingprocesses(Tongetal. 2010).
SolidAcidCatalyst
Solidacidcatalystshavevariousbenefitsoverliquidacidcatalystsasitfacilitatesthe separationofproductthateventuallycanberecycledwithoutlosingtheactivityand itminimizesthecostofpost-treatmentsuchasneutralizationandeffluentprocessing; itcanevenworkathighertemperatures,thereforereducingthereactiontime.Solid acidcatalystsarebasicallyaBronstedorLewisacidanditisofvarioustypessuch asVanadylphosphate,ZrO2 ,zeolites,inorganicoxides,andion-exchangeresins.
BronstedorLewisSolidAcidCatalyst TheseseriesofLewiscatalystincluding WOx /ZrO2 ,C–Al2 O3, Zr–P,SiO2 –Al2 O3 ,andHYzeoliteareusedformainlyaqueous phasedehydrationofxylose(Lietal. 2015).Fewstudieshavecharacterizedthe concentrationofbothLewisandBronstedacidsetoftheseseriesofcatalystwith FTIRandTPDspectroscopybyusinggas-phaseNH3 andcomparedthecatalytic selectivityandactivitywithhomogeneouscatalystactivitiesforthedehydrationof anaqueoussolutionofxylose.ThecatalystselectivityisaprincipleoftheBronsted toLewisacidsiteratiooftheheterogeneousreaction(Nandiwaleetal. 2014).Lewis acidsiteslowerfurfuralselectivitythroughcatalyzingasidereaction.Inthehotwater (190°C),solidLewisacidspromotedthecellulosedepolymerizationandlowered thecreationofsolubleoligomersandpolymersasinconnectiontothecelluloseselfhydrolysiswhichoccurredinthefamiliarconditions(Chengetal. 2011).Bycontrast, innormalconditions,strongBronstedsolidacidhasnotimprovedtheextentofthe cellulosedepolymerizationbuthasaffectedtheproductdistribution.Ithasbeen discoveredthatthenormalproductofsolubleBronstedacidcatalystincellulose depolymerizationlikeglucoseandHMFwasnotgeneratedthroughtheconversion processbutlacticacidsandlevulinicwereaccepted(Weingartenetal. 2013).Ifwe compare,Lewissolidacidswerenotonlypotentialtoupgradetheextentofcellulose depolymerizationbutalsofavorablefordirectformationoflacticacid,whichgives highyield,approximately30%.Thiscomparisonrepresentshighlypotentialways tooptimizetheconversionofcelluloseandstabilizeBronstedacidcatalystwhich helpstounderstandthereactionpathways(Zhaoetal. 2011).
ThisalsobroughtanideaforvariousresearcherstostudytheeffectofBronstedaciditiesofwater-solubleheteropolyacidcatalyst,knownasHPA.ThisheterogeneousHPAcatalystismicellar,clean,economical,facile,andenvironmentallyfriendlyprocesswhichcouldberecycledviacentrifuge(Huetal. 2012).The exhibitingactivityforthehydrolysisofpolysaccharidescomprisingdisaccharides, starchandcellulose,isknowntobeHPA.Tungstophosphoricacids(H3 PW12 O40 ) andtungstosilicious(H4 SiW12 O40 )arethevigorousacidusedintheseriesofHPA asacatalystinreactionofhydrocarbonsandhasbeenemployedforexample,in
alkylation,acylation,esterification,dehydration,andisomerizationoftheethanol process.SaltofacidiccesiumH3 PW12 O40 ,Cs2.5 H0.5 PW12 O40 (Cs2.5 H0.5 PW)with intenseacidityisinsolubleinorganicsolventsandwater,andhasmeso-andmicroporeswithrelativelyhighsurfacearea(130m2 gk).ThisCs2.5 H0.5 PWhasbeen describedasasolidacidcatalystwithprudentandenvironment-friendlyspecifications,andisrecommendableinindustrialprocesslikehydrationofolefinsorester andliquid-phasedehydratedalcohol.Tillnow,cellulosehydrolysisintosaccharides employingarangeofHPAcatalysthasbeenresearchedforcapableapplications, incontrasttoconventionalacid-catalyzedreaction,whereastheyieldofglucoseis less(PatilandLund 2011).Itisbecauseoftheinsolubilityofcelluloseinanyof solventandproblemsofsolidtosolidmasstransport.Inafewcases,theacidityof mineralacidislowerthanthatofHPA.Forexample,(H0 )ofH5 BW12 O40 (0.7Mat 100°C)theHammetacidityfunctionis 2.1lowerthanthoseofHCl(0.7M)and H2 SO4 .Hence,HPAshavebeenanticipatedtobereusableandactivecatalystfor thehydrolysis.Alongwiththattheory,amorphouscarbon-bearingSO3 H,COOH, andOHgroupshadbeendescribedtoshowhydrolysisactivity(10%ofglucose yield)for3hat100°C.Meantime,Yabushitaetal.demonstratedthatthecellobiosehydrolysisandcelluloseinwaterassistedbyHPAssuchasSn0.75 PW12 O40 , H3 PW12 O40 ,andH4 SiW12 O40 recordstotalyieldsofdecreasingsugaranditwas around40%at200°Cfor16hofreaction(Yabushitaetal. 2014).Ithasbeen foundedbyHarathatH5 BW12 O40 exhibitedagoodperformanceforthetransformationofcrystallinecellulosetogiveglucose77%yieldandvarioustypesofHPAs likeH3 PW12 O40 (glucoseyields8%)andH4 SiW12 O40 (37%)whicharelessactive thanH5 BW12 O40 .Otherresearchgroupsalsoadministeredthescreeningofcounter cationsofPW12 O40 forthecellobiosehydrolysisandtheyfoundthattherewasa volcano-typecorrelationbetweenLewisaciditiesandTOFsforglucoseformation (Chambonetal. 2011).TheyalsoobservedthattheacidityandtheroleofdecreasingCrIwerethesignificantfactorsforthecatalyticactivityofHPAs.Inreality,the H0 rolewasH3 PW12 O40 <H4 SiW12 O40 <H5 BW12 O40 inthesimilarorderofcatalyticactivity.TheH0 roleswerecorrespondingtotheconcentrationofacidsandthe numberofanions.Hence,HPAsinvolvinghighlynegativelychargedionswhichare desirable.Theanionsweredissociatedfromhydrogen-bondingbetweencellulose moleculestolowertheCrI.Moreover,HPAsprotonshavealsoexhaustedthebonds ofhydrogenfromcelluloseandgreaterconcentrationofprotonswaseffectiveinthis role.Therefore,astrongcatalystforthecellulosehydrolysisisH5 BW12 O40 ,which wasrecoveredthroughtheextractionanditwasrecycledforaround10times.
Ion-ExchangeResins
Sulfonicacidfunctionalitiesofion-exchangeresinwithsolid acidcatalystandsulfonicacidfunctionedmaterialsresultedinhighyieldat63and 76%inpuredimethylsulfoxide(DMSO)solvent,correspondingly(Leeetal. 2014). SolidacidssuchasamorphouscarbonmaterialsconsistingofSO3 Hgroupslayered transition(HNbMoO6 )metaloxideandresinsulfatedhavebeentestedforthecellulosehydrolysis,buttheyieldofglucoseisstillcomparativelyless.Ithasbeen hypothesizedthatsidereactionswereabolishedemployingaproticororganicsolvents(JohnsonandPanas 2000).Vigorousacidicresins(AmberliteIR-200andIR-
6S.BagheriandN.MuhdJulkapli 120),niobicacid,mixedoxides(silica–zirconiaandsilica–alumina),silica–niobia, andniobiumphosphatecreatedastrongaciditywhichwasprotonic,andaccessibilityofsimplesaccharidestothemosteffectivesitesonthesurfacecatalystallows satisfactoryreactionratestobeobtained(Suganumaetal. 2008).
Sulfonicresins,whichareacidic,arerepresentedindifferentliteraturesasactive systemofcatalyticforthehydrolysisofstarch,cellulose,anddisaccharides(Shimomuraetal. 1967).Generally,therigidconditionsintermsoftemperature(>120°C temperatureinthewaterandincriticalcondition)andhighconcentrationofsaccharide(>100g)wereemployedtopushthecatalyticactionsofsolidacidtowardthe achievementofhightransformations(Igarashi 2013).Sulfonatedactivatedcarbon couldtransformcelluloseofamorphousintoglucosewith41%ofyieldfor24hata temperatureof200°C.SuchthingshavebeenfoundedbySunandZhangSchaller whodemonstratedthatp-toleunesulfonicacidcancatalyzecellulosehydrolysisin ionic[EMIM][Cl]system,givingTHFyieldsof28and13%andayieldofmonoanddisaccharides10and3%,respectively(HeinzeandGericke 2014).Naturalbamboocanbeconvertedbyasulfonatedbiomasscharwithcottonandstarcharound 20%yieldofglucoseundermicrowaveassistance(Kolleretal. 2015).Theprocess ofhydrolysisconsistingofstarchandcellulosewasobtainedvialayeredtransition metaloxide,despitetheyieldfromglucosewaslessthancellulose.SulfonatedcarbonwithamesoporouslikestructurewasusedbythegroupsofVyverforcellulose hydrolysisgettingtheyieldofglucosearound75%,whichisconsideredtobehighestrecordedyieldviasolidacidcatalyst.Similarly,someinteresthasbeenshownin cellulosedepolymerizationinwaterbecausesolid-supportedacidcatalysiswasused (dosSantosetal. 2013).
Currentreportsdescribethecellulosehydrolysisbysolidcatalystssuchaslayeredtransitionmetaloxides,Amberlystresinacidmodifiedamorphouscarbonand sulfonatedsilicaorcarbonnanocomposites(Leeetal. 2012).Also,thecellulose depolymerizationofcellulosewasconsideredundercatalyzedofbothFeCl3 and nafionsupportedbyamorphoussilicatobetestedonacontinuousflowreactor, giventheresidualthatunreactedcellulosecanbeeasilyeliminatedfromthesystem. Fortheconversionofglucose,thesesurfacespecieswhichareacidicwerequite active.Certainly,weareawarethatthehydrolysisrateofcellulosedependsonthe acidstrength.Asanexpansiononpreviousreportsusageofnafionasasolid-assisted acidcatalystforthetransformationofcelluloseintoglucoseandlevulinicacid, manyresearchershaveincorporatedthereactionwithalkalimetalsaltstoembrace thereaction’syield(Akiyamaetal. 2011).Klamrassameeetal.andNamchotetal. haverecentlyformulatedcarbon-basedsolidacidwithimmensedensityofBronsted acidsites(SO3 HandCOOH)topyrolyticallycarbonizesugar,suchascellulose, sucrose,orglucoseandsubsequentlysulfonatethepreparedcarbons(Weerasaietal. 2014).Interestingly,thesesulfonatedcarbonmaterialsareverystrongforthemicrocrystallinecellulosehydrolysistoproducewater-solublesaccharidesatlowreaction temperature(100°C)withtheconventionalandstrongBronstedacidcatalystsuch asH-mordenite,niobicacid,andothers.Theparticularsurfaceareaofthesulfonated carbonwasaround2m2 g 1 butthesolublesaccharidesyieldreachednearly70%.
Catalyticperformanceofsolublesaccharideswasappliedtoitsintrinsicabilityto
adsorb β-1,4-glucan,whichisnotabsorbedontheothersolidacids.Thus,itcanbe concludedthatheterogeneouscatalysisismoreactiveandenvironmentallybenign, mainlybecauseofahastyproductseparationandalsocatalystrecovery.Takagai etal.describedthatacidresinswithconsiderablybigporescouldactivelydepolymerizecelluloseinionicliquid,butthemainproductswerecellooligomerswhich werefailedtobedissolvedinwater(MastersandMaschmeyer 2011).
ZeoliteCatalyst
Crystallinemicroporoussolidsareanimportantpartofzeolitesbecauseofits widespreadapplicationinabsorption,separation,andcatalysis.Itsimportant stemsfromitsuniquestructuresofpores,whichmakesithighlyparticularto absorbmoleculesforseparationreasonsortowardproductmoleculesincatalysis (Chen 1996).Furthermore,duringheterogeneouscatalyticreactions,itshowsgood hydrothermalandthermalstabilities.However,fromthelast20years,therehave beenmanystudiesthatfocusedonthecatalytictransformationofbiomassandits derivedfeedstockswithavarietyofzeolitecatalysts,includingFerrient,FCC,AlMCM-41,ZSM-5,Betazeolite,Yzeolite,SSZ-20,IM-5,TNU-9,MORmordenite, SBA-15,Al-MSU-FFER,ZSM-23,MCM-22,andMFI(Louisetal. 2011).ZSM-11 andZSM-5amongtheseserieshadthelowestamountofcokeandthehighestyield ofaromaticbecauseofitsporespaceandstericeffects.Manufacturizationofordered porouscarbonmaterialhasbeenobtainedpreviouslythroughreplicationofordered zeoliteinorganicandnanocasting.Insidezeolite,manyreactionshaveoccurredwhich includesdecarbonylation,dehydration,isomerisation,anddecarboxylationandwith thatremovingoxygenascarbondioxide,water,andcarbonmonoxideandconversionofcarbonandhydrogenintoaromaticsandolefins(Azeezetal. 2011).Inthese catalystsofzeolite,ZSM-5hasexhibitedthehighestolefinandaromaticyieldsfrom biomassoflignocellulosic.Withaporesizeofaround5.5–5.6A,ZSM-5hasa three-dimensionalporesystem.Thissmallsizeofpore,internalvolume,andinternalstructurehasmadeitproblematicforgreateraromaticcokeantecedentstoform insidethepores(Manteetal. 2013).
MetalIonCatalyst
FurfuralandHMFarethetwomainandsignificantintermediateswhicharederived frombiomass.Theyweredirectlymanufacturedfromthemicrocrystallinecellulose hydrolysiswithmetalionsinionicliquidssuchasFe3+ ,Fe2+ ,Cr3+ ,Co2+ ,andMn2+ asacatalystundermildconditions(Williamsetal. 2012).Metalionsasanacidic supportareanicecatalystforhydrogenationandringopeningofcellulosepolymers. Manyreportsarethereoncarbonproductionthroughcellulosehydrolysisata moderatetemperatureupto250–300°Cmetalcatalystinaverylessreactiontime tocontrolthedeepexploitationoftheformedglucose(VuyyuruandStrasser 2012). SomeresearchersevenusedRuthatisarutheniumcatalysttoenhancethetransfor-
8S.BagheriandN.MuhdJulkapli
mationofoligosaccharidesandincreasedglucoseyield(almost30%)withtheTON thatistheturnovernumberofthecatalystwasimmense(145basedonbulkRu)in contrasttothoseofthesulfonatedcatalystsofcarbon(Dreheretal. 2013).Wang etal. 1993 foundedthattheglucoseyieldwasincreasedaround31%byupgrading theRuloadingto10wt%alongwiththerecyclableamountofcatalystuptofive timeswithoutlosingtheactivityorRuleaching(Wangetal. 2012).Variousreports ontheefficiencyofthehydrolyzedcelluloseformulatedbyRucatalysisassourcesof carbonforthebacterialPHAproductionandfoundedthat,undertheaqueoussolutionthereactionwhichoccursisdesirablefordeliveringtomicrobeswhichthere uponmakesiteasilydisconnectedfromyieldedsugarviafacilitatingtheraceofthe catalystandfiltration(Ashiketal. 2017).SuchreportshaveacceptedthatRuspecies wereinfactinanoxidizedstateactedastherealandeffectivesitefortheoligosaccharideshydrolysis.Prior,Ru/Co3 O4 catalystshaveshowedconsiderateselectivity andactivityandgoodrecyclabilityinthebiomassconversiontocarbon.
MetalOxideCatalyst
Inmanycatalyticprocesses,metaloxidesplayanimportantrole.Forexample,metal oxidenanostructuresareimportantcomponentwhicharecommerciallyavailable forsynthesisofmethanol(Liuetal. 2016).Therearemanymorebenefitsofthese catalystswhichmakethemefficientcandidatesforgreenprocesses.Thecharacteristicsofsuchcatalystsarestable,nontoxic,lowcost,availability,nonvolatility, andreusability.Severalstudieshaveobservedtheprocessesofdecompositionconnectedwithformicacidonnano-metaloxidesurface,methanol,andformaldehyde. Itisstronglyexpectedthatmetaloxidenanostructureswouldhaveabettercatalytic activityindevelopingtheconversionofcellulosetothevalue-addedproductsin hydrothermalmediawithanefficientseparationfromthereactionmatrixinregard totheincreasedsurfaceareaofthenanomaterials(Lietal. 2013).Layeredtransition metaloxidescontainingniobiumfoundtobespecificallyactiveinthehydrolysisof disaccharide,suggestingtheimportancetoinvestigateniobiumcontainingcatalyst asanenergy-inefficientfactorfortheconversionofbiomass.
TheemploymentoftransitionmetaloxidelikeHNbMoO6 wasalsoreportedasan efficientsolidcatalysttogenerateglucosefromcellulose.Similarly,inthepresence ofnoblemetalconsistingofcatalyst,forexample,Pt/Al2 O3 ,Feliceetal.havefound thecreationofsugaralcoholsinyieldupto31%fromcelluloseinhydrothermal conditions.Ontheotherhand,theresearchersproclaimedthatPt-freecatalystshave generatedonlypoorglucosehexitolsamount.
1.3PhotocatalyticSystemswithActivatedCarbon
Theactivatedcarbonisacarbonaceousmaterial,whichstructuredonplant-based material,isaporous,amorphoussolidcarbon.Well-developedporoussurface,pro-
videdwithhighporevolumeandextendedsurfacearea,makesactivatedcarbonthe mostcommonlyusedtechniqueforcontrollingpollution.Well-developedporesover thesurfaceareoneofthemainusesofactivatedcarbonasthephotocatalysissubstrate.Nontoxic,chemicalstability,andbeingeconomicalarethemainreasonsthat inpastdecadestheheterogeneoustechnologyhasgotmanyattentions(Khanetal. 2014).Astheorganicpollutantscanbemineralizedintoneutralbyproductssuchas H2 O,CO2 ,andmineralacids,oneofthemainpropertiesofheterogeneous-activated carbonphotocatalysismethodsincludesthedestructionofthewidercategoryof organiccompounds.Promotingsolarradiationandworkingonthelowtemperature, eventuallysavingalotofenergy,makeitveryeconomical.Oneoftheadvantages oftheactivatedcarbonincludestheregenerationofspendingabsorbent,anddemolishingofabsorbedorganicmaterialonthesiteisconvertingthelossofabsorbents toburnthemconcludingthatthermalregenerationisefficient(McEvoyetal. 2013). Activatedcarbon,beingthestronglight-absorbingcompounds,hasbeensuccessfullyusedasphotoactivespecies.Determiningthebandgapoftheactivatedcarbon (bandgaplessthan4eV)resultedinbeingasemiconductorandthereforeasphotoelectricmaterialsinthepresenceofultravioletradiations(Khanetal. 2014).Recent reportssuggesttheabnormalreactiontowardtheaqueousenvironmentbydirecting ultravioletirradiationofthesampleinthepresenceoftheactivatedcarbonprovided thatnootherphotoactivematerialsarepresentshowingthattheactivatedcarbon improvedthephoto-oxidationofphenol,beyondthedegradationofphotolysisin comparisontobareorunmovedtitania(Velo-Galaetal. 2013).Tofindthedifference whetherthisreactionisonlyshownbytheactivatedcarbonoralsobyothercarboncompounds,someresearchershaveworkedondifferentporousactivatedcarbon materialsobtainedfromdifferentsites,procedures,andreactionsandtheirbehavior totheexposedultravioletradiations(Pamechaetal. 2016).Thefinalsolutionisto removeanyvaguenessinresultthatinaqueousmedium,ultravioletradiations,and absenceofsemiconductoractivatedcarbonareabletodemolishtheorganicmaterialsintherespectivconditions.Regardlessofthetype,activatedcarbonactsasa catalystduringremovalofdiatrizoate.Gammaradiationsbasedonactivatedcarbon ismoreefficientinawaythatitisahigherproportionofCatomsandcontains sp2 hybridized(Nishidaetal. 2004).Withmorethan53%ofsynergisticeffectin diatrizoateinthefirstminuteofreaction,commercialcarbonexhibitsitfromthe ultraviolet/activatedcarbonsystem.Providingmoreoxygen,thesynergisticactof activatedcarbonisboostedup.Thereutilizedactivatedcarbonisquitesimilarto originalC;thepresenceofOinthesampleincreasestherateofremovingofdiatrizoatebytheultraviolet/activatedcarbonsystem,buttheultravioletinclusionof systemresultsinsomemodificationsinactivatedcarbonchemically.Thereisavery vaguerelationshipbetweenthetextualpropertiesandthesynergisticcontributionof theactivatedcarbon.Gammaradiationinvolvementwithactivatedcarbonreduces thebandgapthatresultsinmoreefficientremovaloforganiccompounds.Oneofthe actionsproposedintheresultsandevaluationsthattheactivatedcarbonisthephotocatalysissubstratewhichwillpromotetheelectronsfromthevalencebandtothe conductingband,resultinginenhancedgenerationofOH-freecompoundspresent inthepollutingmedium.
1.3.1EffectofSurfaceProperties
Manyresearchersandauthorsreportedmanysurfaceandtextualfeaturesofactivatedcarbon.Itisclearthatbasicactivatedcarboninthepresenceoflowoxygen inthismediumismuchmorepotentialofthephenoladsorption.Anincreaseinthe physicalabsorptionandsurfacepolymerizationofphenolscanbedonebyensuring thedeprivationoftheacidiccategoriesonthesurfaceoftheactivatedcarbon.Irreversibleabsorptionandcatalyzingtheoxidativecouplingofphenoliccompounds canbeenhancedbytheO2 containingbasiccategoriesoverthefaceofactivated carbon.Boostinguptheinteractionsbetween π–π electronsinactivatedcarbonand phenolsisduetothegraphenelayersofanactivatedcarbon,whichincreases π electrondensity(Elangovanetal. 2015).Incarbonofbasicnature,phenolisconsidered tobehigherbecauseofbeing,regardlessoftextualproperties,absorptioncapacity. Retentionofphenolissupposedtobecomelessintheacidiccarbonascomparedto thebasiccarbon;infact,thereisnoclearrelationshipbetweentwo.
Oneofactivatedcarbondrawbacksisthatthewasteorganicmaterialsnotreally destroyedbutaretransformedfromonephasetoanotherandinresulttheused activatedcarbonistransformedintoadangerousproduct.So,regeneratingactivated carbonbecomesnecessaryforitsreusability,whichmakesaneconomicalprocess. Theactivatedcarboniscarryingsomelimitationslikeitsadsorptioncapacity,which isafunctionofinertconcentrationthatresultsinlow-qualityproducts(Babadietal. 2016).Alreadyusedactivatedcarbonistobedisposedofasitishazardousmaterial orregeneratedtobeusedagain.Thermalregenerationcontainsmanydisadvantages becauseofitsoff-siteregenerationthathardlyconvertsthepollutantfromonephase toanother.Thismayresultduetodepletionofcarbonandmaycausedamagetothe structureofactivatedcarbon.
Theprocess,whichcouldproducehighyieldefficiencies,couldbeachemical regenerationofspentactivatedcarbonbutithassomedrawbacksregardingchemicalconsumptionnondestructivepollutanteliminationandcreationofunimportant steamsofwaste(Eliyasetal. 2013).However,techniqueslikeultrasonicregeneration,microwaveregeneration,andelectrochemicalregenerationarealsobeingproposedasalternativetechniquesfortheprocessofchemicalregenerationofspentAC. Duetothelimitationsofthepresenttechnique,thereisaneedtodevelopanother technique,whichismoreeconomicalandenvironmentalfriendly.Thus,tomake onehybridsystem,thereisaneedtomergesemiconductorwithactivatedcarbon. Organicpollutants,issuesofdestruction,andotherhazardousproblemsareexpected toarisefromtheoxidationsemiconductorelement.ThereasonliesinthegenerationofradicalspecieslikeO• andOH• fromthecatalystparticlesofsemiconductor, whichcausesoxidationofsuchspecies.Anothertechniquethathasbeenstudiedfor activatedcarbonisthecombinationofheterogeneousphotocatalysisandtheFenton reactionwiththecatalyticprocess,whichisanoxidation-basedprocess.
Studiesonthisspentactivatedcarbon,whichcarriedoutpreviously,weremostly aboutgranularAC.Takeanexamplewhichdemonstratedthattherewasimproved efficiencyinherbicideremovalfromthewaterwhengranularactivatedcarbon
adsorptionphotocatalysissubstratehybridsystemwasusedincomparisonwitha photocatalysissystem(Babadietal. 2016).Similarly,itwasalsoreportedthatthe combinationofphotocatalyticandrotatingadsorbentshowedbetterefficiencyin removingformaldehydeincomparisonwithadsorption(Xuetal. 2014).
1.3.2ActivatedCarbon/TransitionMetalOxide PhotocatalysisSystem
Byimpregnationandadsorptionalongwithvariousmethods,metaloxidesare expectedtobeimpregnatedintothesurfaceofcarbon;allthesame,thisisapplied forcomplexexperimentalproceduresandprocess,whichoperateathightemperature.Consideringidealconditions,aphotocatalysismaterialshouldbeinexpensive, highlyproactive,andnontoxicandstable.Onemorecriteriathatplayaroleinthe degradationoforganiccompoundsisthatthepotentialoftheredoxresidesinthe bandgapofthesemiconductor.Therearemanysemiconductorswiththebandgap energiesampletocatalyzeseveralchemicalreactions,whichincludeWO3 ,Fe2 O3 , SrTiO3 ,ZnS,titania,andZnO(YangandBai 2014).Themetalsulfategroupwith insufficientstabilityintheprocessofcatalysisiskids,PbS,orCdS.Thiscompound undergoesphoto-anodiccorrosionreadilyandistoxic.Forexample,Fe3 O4 undergoesphoto-anodiccorrosionreadilysotheyarenotsuitable.ZnO(3.2eV)isunstable withZn(OH)2 inwater,andalsoithasabandgapsimilartoanatase,soitresultsin thedeactivationofthecatalyst.
1.3.2.1ActivatedCarbon/TitaniaPhotocatalysisSystem
TitaniaPhotocatalysisSystem
Themostpromisingsemiconductorforphotocatalyticdestructionorganicpollutants istitaniumdioxide(titania).Itprovidesthemostexcellentagreementinaqueous mediabetweenstabilityandcatalyticperformance.Sinceitisnontoxic,cheap,biocompatibility,andstabilityinsunlight,itisofimmenseimportance;thatiswhyitis alsoconsideredusablecleaningenvironmentaloperations.Consequently,theelectronpairsandpositiveholesarecreatedatthesurfaceoftitania.Onceithasbeen irradiatedwiththeUVlightofthewavelengthof380nm,titaniawouldformreactive oxidants,e.g.,OHradicals,hydrogenperoxide,superoxideanions,andotherreactivespeciesofoxygenandreactionsthatarereductive,tocontributeintheorganic compounddecomposeswhichareadsorbedonthesurfaceoftitania(Zhangetal. 2014a, b).Thehighestphotocatalyticdetoxificationoftitaniaisanatasephase.Deep studieshaveshownthatphoto-degenerationsofcomponentslikeherbicides,phenols, dyes,pesticides,surfactants,andorganiccomponents(e.g.,salicylicacidandsulfosalicylicacid)havebeenpossessedbytitaniathatispresentinwaterwastes.titania
powderscontributedtosomedrawbacksinseparatingphaseinphotocatalysis,with purposeofitsemissionintheatmospherebecauseoftheirsmallsizeoftheparticles andrecovery,thelossofphotocatalysissubstrateiftheseparationisnotpromising, theneedoffluidizationofthepowderingaseousphasewithcostandenergy,andthe scalingdifficultiesinvolved(Amiretal. 2015).Also,sinceradiationfromthelight compromises47%visiblelight,48%infraredradiation,and5%UVlight,titania actsasabenchmarkofUVphotocatalysisthatitgoesdeactivatedundervisiblelight becauseofitswidebandgap(Amiretal. 2017).Movingon,theholesandphotogeneratedelectronspresentinanexcitedstateplayavitalroleinthedegeneration ofpollutantandareunstable;andwithoutanyeffortitcanrecombineanditleads tolow-orderefficiencyresultsofphotocatalysisactivities.Itisclearthattheuseof highpotentialsolarphotocatalysiscannotbemadebytitania.
Titania/ActivatedCarbonPhotocatalysisSystem
Foreasymanipulationinaprocessoftotalphotocatalyticoperationandquickdecompositionoforganicpollutants,itmightspeeduptheprocesstoloadphotocatalysis tosuitableadsorbentstoincreasethestrengthofpollutantsaroundthephotocatalysissystem.Therefore,researcherhadmadeattemptstosupporttitaniaondifferent matrixesassilicagel,clay,carbonmaterials,alumina,andzeoliteswhichcanbe nanotubes,carbonmicrospheres,carbonblack,carbonnanofibers,andactivatedcarbon(Zhangetal. 2010).Titaniaparticlesarehydrophilicwhenexposedtodirect UVlight,whereasorganicpollutantsarehydrophobic.Theuseofactivatedcarbon asareferencewillprovidehelptomoleculesofpollutantclosertotheactivesiteof titaniaforaquickandeffectivephoto-degenerationprocess.Theactivatedcarbon tofavororganicpollutantsthatareapproaching,inwhichsecondarydegradationto takeplaceintermediatelyinsitucangeneratenewadsorptioncenters.
Ingasandwaterremediationforsupportpurposes,activatedcarbonisusedwidely becauseofitshighporosity,goodadsorption,supportedtitania,andlowcostthat hasmarkedtheeffectsondisappearanceofpollutantskinetics,witheachpollutant beingmorequicklydegenerated.Forexample,thetitaniasurfaceismadestaticover glasssurface;ithasthebenefitslikehighphotodegradationproductivity.Themajor limitationistheadhesionforceintitaniamembraneandglassispoor,sotitaniais easytodecrease,whichcausesthedecreaseofthephotodegradationproductivity.
Hybridoftitaniawithactivatedcarbonsupport,asasensitizerwhichisableto absorblight,wasproventobethebestapproachtodevelopphotorespondingphotocatalysismaterialwithgreatactivity.Theformationofheterojunctionbetween titaniawithasmallbandgapandnegativelychargedactivatedcarbonmayresultin theinoculationofconductingbandelectronsfromactivatedcarbontotitaniaandit isveryusefulforelectronsandholedivision.Atthesametime,theimmobilization oftitaniaontotheactivatedcarbonsupportcancompromiseforthelossofphotocatalyticabilityoftitaniabecauseofthedifficultytoeffectivelydisperseinwater forcompleteinteractionwithpollutants.So,manyresearchersreportedthatthereis anoptimumtitaniathatusesamountandactivatedcarbonporeformationforattain-
ingthehigherphotocatalyticproductivitythantitania(Bagherietal. 2012).The3-D relationbetweentheparticlesofactivatedcarbon,titaniaasaphotocatalystsubstrate withsmallparticles,andthemoleculesoforganictoxicisreportedtoberepresentationalintheabsenceoflightandinthepresenceofultravioletenlightenment.The organicpollutantsaresupposedtobesmalltoadsorbinmicrospores.Inmostofthe activatedcarbon,alargegroupofmicroporesexistsoverthebroadsurfaceofthe substantialpores,mesoporesandmacropores;alargeamountoftoxicparticlesis wellbalancedduetophysicaladsorption(Zhangetal. 2012).Instead,onlyalittle numberofpollutantparticlesareadsorbedonthesurfaceoftitania.Bydepositing titaniamoleculesontoactivatedcarbonparticles,somemesoporesandmicropores becomeclosertotheiropeningsandthiscausesamarkedlessenintheuncovered surfacearea.Theultravioletenlightenmentoversuchtitaniausedactivatedcarbon molecules;oxidativeOH-freeradicalstakebirthonthetitaniaandcandestroytoxic moleculesbyoxidation.
Themovingforceofmigrationisactuallythesaturatedgradientbetweenorganic toxicparticlesovertheenlightenmentoftitaniainterfaceandontheotherside someoverthesurfaceofchangingporesizesoftheactivatedcarbonmolecules. Themoleculesdiffusedinsidemicroporesofactivatedcarbonmigratewithgreater retaliationtowardtitaniamoleculesresidedontheinterfaceoftheactivatedcarbon particles.Thus,highlymicroporous-activatedcarbonparticlesarenotusuallyadvantageousforthetitania:activatedcarbontohavepreferredthephotocatalyticresponse (Bagherietal. 2012).Theeffectofthesubstrateporeskeletonhasbeenobserved usingactivatedcarbonsurfacearea(770–1150m2 g 1 )andadip-hydrothermalprocessofphotocatalysismaterialpreparation.Improvedphotocatalyticdemotingof methylorange(MO)hasbeenattainedwithtitania:activatedcarbonthanwitha simplemixtureoftitaniaandactivatedcarbon.
Thisgotintothedesignofhighlyeffectivetitania:activatedcarbonhybridheterojunctionphotocatalysissubstrate,andalsothedemandofcommonsensiblecrosscheckcapacityofbandpotentialsamonghybridmodules,thespatiallyandflataccessibletransmissionofholesandelectronattheexposedsurface,andtheholeand electronmovementofthehybridsystemareimportanttoenhancethephotocatalytic action.Ithasbeenreportedthatthesurfacechemistryandmapofactivatedcarbonrevealedmajoreffectonthecollectionoftitaniaparticlesandphotocatalytic deprivationof4-chlorophenol.Addingtothis,someresearchershaveconstructed titaniawithactivatedcarbonmicrospherestobothmaintainspreadingandspeeding upseparationduetotheactivatedcarbonmicrospherethatcanbebalancedwith airybubblyanditcanbespeedilysettledinthereactorbasewiththehelpofsome gravityduetotheairbubbles.Inaddition,someauthorshavefabricatedtitaniawith activatedcarbonmicrospherestobothsustainspreadingandaccelerationdivision, becauseactivatedcarbonmicrospherecanbebalancedwithairbubblesandbeable tospeedilysettleontopofthereactorbasebygravityduetoairbubbly.Toovercome thisshortcoming,theuseofco-binderupholdingtheexpansionofanothermethod toobtainafreshformofthetitania:activatedcarbonphotocatalysissystemforsuch ahighactionandbetterdivisionperformance.
Therefore,mostsampleswhichwerecookedathighertemperaturewerevery detrimentaltophotoactivity.Also,usingdifferenttypesofactivatedcarbonrevealed theconnectedeffectsbetweentitaniaandactivatedcarbonduringthe4-chloro-phenol photodegradationandfoundaclearenhancementofphotoactivityduetoanincrease inelectrondensityoftheactivatedcarbonsupport(Kuoetal. 2014).Itisresearched thatattendanceofactivatedcarbonininteractionbytitaniahelpsduetoitsburly adsorptioncapability.Inthesameway,itadvancestherelocationrateoftheinterfacialchangeaswellaslessentherejoiningrateoftheholesandelectrons(Jungetal. 2013).Thissynergisticeffectoftheinteractionofactivatedcarbonandtitaniahas beenpreviouslybeenstatedfordeprivationofsomeorganiccompoundsinthephotocatalyticprocess.Ithasbeencreditedtoacommoncontactbetweenthedifferent solidphases,inwhichactivatedcarbonactsasanefficientadsorptionagentforthe organicpollutants.
Theorganicmoreefficientlymovedtothetitaniasurface,whereitisimmediatelyphotocatalyticallydegradedbyamassmovementofthephotoactivatedtitania. Thus,theorganicburningrateobservedontitania:activatedcarbonislikeheading bothwithsurfacediffusiontoxinparticlesandwiththephotocatalyticprocessrate; becauseadsorptionoccursgradually,thevariationinrelativepollutantproportion withirradiationtimedependsonbothadsorptionandphotodecomposition,mainly atthestartofultraviolettreatment.Itisstatedthatthevarianceoftheproportion ofphenol(asmodeloforganicpollutants)remaininginthesolutionbyultraviolet treatmenttimeiscomparedfortitania:AC,whichwerepreparedbyhydrolysisof tetraisopropylorthotitanateandheattreatmentat650–900°C.Forexample,itisnoted that,inthedurationoffirst1h,adsorptionofpHoccursinnative-activatedcarbon andafter3h,inthepresenceofUVirradiations,saturationisachieved.Adsorption aswellasthephotodecompositionofpHtakesplacesimultaneously,butontheother sidetheformerissupposedtobecomethedominatemethodinthebeginning,similarlylatterinthenextstage.Thenotedtrendwasbasedontwolinearprocesses;the changeofoneprocesstotheanothertakesplaceapproximatelyin1hofirradiation.
DesignofMaterial
Anumberofmethodsareavailableforthecompositionoftitania:activatedcarboncatalyst,suchasprecipitation,chemicalvapordeposition(CVD),hydrothermal, aerosolpyrolysis,hydrolysis,dipcoating,andsol–gel.However,selectionprocess whichisusedfortheselectionofasuitableimpregnationmethoddependsonlyon supportusedinitandthepollutantwhichisdegraded.Itisclearthatthosephysicochemicalpropertiesoftitania:activatedcarboncatalysthaveaheavyimpactonthe structureofthesupportedcatalyst,anditdependsbasicallyonthepreparationmethod used,forexample,thermaltreatments.Themainadvantagesofusingphysicalmethodsaresimple,lowcost,andtheuseofcommerciallyispresentinphotocatalysis materialwiththewantedfunctionalities.Byusingthewetmethodsthehybridof titania:activatedcarbonwasalsobeingprepared,themismatchesintheleveloflatticeamongtwohybridcomponentslessentherequiredefficiencyofseparationand
transmissionofphoto-generatedcarries(electronandhole)(Lietal. 2012).Adherenceofactivatedcarbonsurfacetotitaniaparticlesappearssignificantforincrement ofphotocatalyticactionandaswellforusefulapplicationsofhybridsystem.To increasetheanchorageoftitaniaonactivatedcarbon,thewetprocessofsynthesisis warranted.Thisisonlybecausethephysicalstablehybridoftitania:activatedcarbon indisagreementwithhydrodynamicshearingmethod,surfacechemistryplusactivatedcarbonporestructurecanhaveasufficientimpactoverspreadingoftitaniaover thesynthesis;itresultsinthedifferentphotocatalyticpresentationsoftitania:activatedcarbon.Nevertheless,titaniaphotocatalysissubstrateusuallyhaslowprecise surfaceregion.Duetocrystallinitydevelopmentwhichhappensinheatoperation likethat.Topreventtitaniasintering,orelsetomakeitprecisesurfaceregionbetter, activatedcarboncanbeexaminedlikeabetterhelpforthephotocatalyticmaterials (Gondaletal. 2012).Theyfoundthetitaniaparticlescalculatedat450°Ccancollect andgothroughthegreatporesoftheactivatedcarbonsubstrate,includingavery burlycontactamongcarbonmatrixandtitania.Thecontactbetweenthemleadsto visiblesynergytoincreasephotocatalyticcapacityforthedegradationofthechromotrope2R.Thepreparednanocrystalanatasetitaniaparticlesinstallontheactivated carbonatafewertemperaturewiththehydrolysisofthetitaniumbutoxideinthe acidicaqueoussolution(Andronicetal. 2014).Itisnoticedthatphenoltoxinwas absorbedbyactivatedcarbon,andafterthatdriftedconstantlyovertitania,which consequentlyacceleratephotocatalyticoxidation.Ontheotherside,thechemical vapordepositionmethodisusedfornanosizedtitaniaparticlesthatwereexposed tosticktoactivatedcarbon,tetra-butyltitaniaandtoofferlargeactivitiesonthe behalfofthephotodecompositionofmethyleneorangeinthewater.Addingofwater intitaniumtetra-isopropoxidevaporswasdescribedtomakepossibleCVDmethod atahigherdepositionrateandlowertemperature.IntroductionofH2 Ovaporsfor thedurationofCVDmethodandadsorptionontheactivatedcarboninpriorwas announcedtobecriticaltogetholdofanatase-typetitaniananoparticlesontheactivatedcarbonsurface.InvestigationshavealsoclearthattheHNO3 treatmentresults inmoreorderlytitanialoadingbyCVD,incomparisonswithotheroxidationtreatment.titania:activatedcarbonhasbeenformedasaresultofusingdroppingthe supportinsolutionproducewiththealkoxidehydrolysisaswell,andsubjectedto heatoperationat300–500°C.Inanalternativeprocess,itcanbeproducedbyadding TiCl4 dropbydropinaqueoussuspensionsofactivatedcarbon,comeafterbyheat operationat500°CinN2 atmosphere(Trybaetal. 2003).Loadthetitaniapowder exactlyoveractivatedcarbonthathasbeenachievedasaresultofcombiningtitania inactivatedcarbonaqueoussuspensionwithstirring.Ontheotherside,loadingmore activatedcarbonfilter,producedasaresultofgluinggranularactivatedcarbonover theglassclothanditwasformedbythewatersuspensionoffivemass%titania,and theconclusiontitania:activatedcarbonparticlesinsideCCl4 solutionofpitch,come afterbyheatoperationat750°C.Inresultanthybridsystem,titaniaparticlesover activatedcarbonwereexpectedlayeredwithcarbon;composedwiththepitchatthe stageoftheheatoperation,itmayfunctiontorepairtitaniaparticleovertheactivated carbonsurfaces.Titaniaparticlesalsowerebeingabletoloadoveractivatedcarbon byspray-desiccationprocedure,withalittlemodificationintheporestructureof
16S.BagheriandN.MuhdJulkapli
theactivatedcarbon(GaoandLiu 2005).Intheotherstudy,loadingoftitaniaover theactivatedcarbonsurfacewastakingplaceviadip-activatedcarbonparticlesina peroxotitanatesolution,andafterheatingat180°CinaTeflonlinedstainless-steel vessel,followingbycalcinationsat300–800°C(Slimenetal. 2011).Withthehelp oftheactivatedcarbonparticlesof0.16–0.26mm,thedisjunctionoftheparticles fromthesolutionwasnottoomuchharder,andphotocatalyticactiononbehalfofthe decompositionofMOalmostremainsidenticalforfivecycles.Titaniahasalsobeen achievedbypluggingtheporeofactivatedcarbonbyparaffin.Afterloadingtitania, byremovingtheparaffinat250°Cintheair,thehighsurfaceregionofpristineAC,it couldberecuperatedaswellasthehighphotocatalyticactionwasprocuredbasically forthedecayofmethyleneblue(MB)(LiandLiu 2012).Titania:activatedcarbon hasalsobeencomposedbymixingtitaniaparticleswithsomeliquidorsolid-state carbonprecursor.Byhydrolysisoftetraisopropylorthotitanate,titaniawascausedin theexteriorregionofthepolyvinylbutyral(PVB)andtitaniaoverloadedPVBwas carbonizedatahightemperatureintheflowofCO2 .Titania-loadedcarbonmicrosphereswith25 μmdiameterhavebeenpreparedfromthetitania-loadedcellulose microspheres,composedwithone-stepstagedivisionusingthesodiumpolyacrylate aqueoussolutionsandcellulosexanthatewiththeisolatedtitaniapowder.
PhotocatalyticActivities
Asamodeloftitania:activatedcarbonphotocatalyticprocesscanbemoreofacomplexissue,itstartsthephoto-intensitytotheclassicalaspectsoftheheterogeneous catalyticsystem,e.g.,temporalvariationsinconcentrationofiminoctadinetriacetate (IT)thatisfrequentlyusedinexcessplusorchardfieldslikeaninsecticide,andinthe waterpathofthefields,itisexposedforpristineactivatedcarbonandthreetitania: AC.Thehybridsystemswerekeptwithoutanylightonthemfor200htosaturate ITadsorptionandafterthatshowingtoultravioletirradiation.After800hbehind this,thesamplewasseparatedfromgivenatestsolutionandspreadoncemorein thevirgin1.87 × 10 4 mol/Lsolution,andagainkeptwithoutanylightinitfor approximately200h,andthenexposedtoultravioletradiations.Asfaraspristine activatedcarbonisconcerned,concentrationofpollutantswasinitiatedtosurvive approximatelysteadywithoutanylightandtospreadtosomeextentbeneathultravioletirradiation.Thebottomlineisthatthephotocatalysissystemoftitania:activated carboncouldhavethesimilarphotocatalyticresultswithoutanylightandunder ultravioletradiations.Beforementioneddatawassupportedbytheonewhostated theenhancementofphotocatalyticactivityfortheorganicburningofpollutantsvia titania:activatedcarbonenzyme.Itisstatedthattheconcentrationof4-chlorophenol solutiondemotesrapidlyforthetitania:activatedcarbonthantitania,sayingthat itenhancesphoto-organicburningapproximatedbyapseudo-first-orderequation withalinearrelationshipbetweentimeandconcentrationchange.ThesameharmoniousresultwasnoticedintheorganicburningofpHand2,4-dichlorophenoxyacetic acidapplyingsimilaractivatedcarbonandtitaniasample.Furthermore,thepHdisintegrationestablishestobedependentuponthemassratiooftitaniatoactivated
1EnhancedPhotocatalyticActivitybyUsingModification…17 carbon(5/10to75/10)(Aruldossetal. 2011).Theharmoniousresultthoughttobe attributabletothefastmovementofpHmoleculesatthestartadsorbedontheactivatedcarbonontheoutersurfaceoftitania;themotivatingforceofthatmovement ismostprobablythedifferentiationinthesurfaceconcentrationofpHbetweenactivatedcarbonandtitania.DefinedproportionofpHwasfoundtoremainatAC,even aftertheproportionsamplebecomesnegligiblysmall.
1.3.2.2ActivatedCarbon/ZnOPhotocatalysisSystem
ZnO/activatedcarbonfindsbroaderattractionofuse,duetosomeoftheexcellent behaviorsofZnO,suchaswideravailability,stability,andsuitablebandgapof energy.ProblemsassociatedwiththeusageofZnOaloneasphotocatalysismaterial areaswellpartitioned;especially,thecomplexityinunravelingthepowderwiththe sampleafterthereactionisoverandgatheringofparticlesindelay,particularlyat highloadingandcomplexityinpurposetotheconsistentflowofthedomainsystem, hasbeenapprovedbyitssurfaceproperties.
TheproblemisthatactivatedcarbonhasbeendeclaredgoodasforthesupportoftheZnOphotocatalysissystem.Replyingonusingofdi-oxygen,photoand entirelymineralizedorganicaswellasinorganicsubstancesandparticularlybiorecalcitrant,makethetechniqueenvironmentallyfriendlyfortoxicwastereduction schemes.SphericalactivatedcarbonparticleshavingZnSandZnOwereformedfrom acation-exchangeresin(polystyrenewithsulfonategroupsandcross-linkedbydivinyl-benzene)andZnCl2 aqueoussolution,followedbycarbonizationatalmost 500–900°C(Wangetal. 2008).ThishasbeenreportedthatZnOisanappropriate substitutetotitaniaforthephotodegradationofAcidRed14,anazodye,becauseit isthephotodegradationprocessesthatarebeingprovedtobesimilartotitania.
1.4ActivatedCarbonPhotocatalyticSystems:Future Trend
1.4.1GranularandSphericalActivatedCarbon PhotocatalyticSystems
InallkindsofAC,thesphericalactivatedcarbonhasbenefits,becauseoftheir frictionlesssurface,high-qualityfluidity,andgoodstrengthofthepowderedand roughactivatedcarbon.Carryingthisforward,manyproposalshavelatelybeen examinedthesustainabilityoftitaniatosphericalactivatedcarbon(Yaoetal. 2012). Buttherearesomestatementsonthegranularactivatedcarbonthatsupportedtitania photocatalysissubstratewhichcouldenhancethedemolishingefficiencyofmany organiccompounds,regardingmanyenvironmentallyrelatedconditions.
Granuleactivatedcarbonsupportstitaniapowderedbyaddingmorepollutants andalternativesaroundthetitania.Thepollutantsandalternativescandiffuseto thesurfaceoftitania.Granularactivatedcarbonalsoreducestitaniajelling,which lessensitssurface,therebyreducingitsenzymaticactivities.Thiswasbroughtbythe theorythattheabsorptivityofactivatedcarbondependingstronglyonthemolecular morphologyandsizeofthepollutantparticlestothetitaniasurfacehappensstraightforwardlyfromthesolution,andnotthroughtheactivatedcarbonsurface.Thetitania candestroythepollutants,leadingtoagaingenerationofgranularactivatedcarbon inthissituation.Mostoftheporousactivatedcarbonisstillingranules,andthe problemofseparationandrecoveringofthephotocatalysissystemfromthereaction environmentisalreadypresent.
1.4.2ACFPhotocatalysisSystem
ThesurfaceareacharacteristicsoftheACFareidentifiedtodependpowerfullyon thecreativeprocesses,affectingtheloadoftitaniaandeventuallytheadsorptionof pollutantparticles.Nevertheless,theACF-supportedtitaniaphotocatalysissubstrate hassometimesbeenusedfortheremovalofgas-phasepollutantsintheenvironment.
1.4.3Graphene/TitaniaPhotocatalysisSystem
Alotofthehardworkisusedforthecombinationoftitania–graphenephotocatalysis hybridsystem(Sinetal. 2011).Duetoahigherspecifiedsurfaceregion,graphene appearedlikeabetterhelptopreparetheoverloadednanoparticlemetaloxidesto attainanidenticaldivisionnotincludingaggregation.Bettermentofthephotocatalyticactionsoftitania–graphenehybridisassociatedwithhugetwo-dimensional planargraphenestructuresupportingthedyeadsorptionplussqueezingelectron— holerejoiningbecauseofhigherelectricalconductionpropertyhasbeenindicatedby themorphologicalanalysisoftitania/graphenephotocatalysissystem.Absorptionof additionalcatalystparticlesintoaparticularlygrapheneleafatindividualplacescan supplybetterdynamicallyinachievingthechoosycatalyticotherwiselogicalproceduresandadjuststhecompositionalsothemorphologyofphotocatalysismaterials toenhancetheirphotocatalyticresults.
1.4.4Titania/CNTPhotocatalysisSystem
Barringgraphene,carbonnanotube(CNTs)hasbeenregardedasamoreattractivecatalyticsupportthanactivatedcarbonbecauseofcombinationofelectronic, adsorption,andspecificsemiconductingcharacteristics.Studiesoftitania:CNTs
revealaconsiderablesynergyeffectwiththemetaloxidesandcarbonphases(Woan etal. 2009).Goingfurther,researchershaveshownthatCNTscanenhancethe adsorptionandphotocatalyticactivityoftitaniainthepresenceofultraviolet.SinglewalledCNTsexecuteenhancedandselectivephotocatalyticoxidationofpH.HeterostructureCNTsconsistsoftitania-xNxandCpreparedbycarbonizationofelectronspunpoly-acrylonitrilenanofiberscontainingstabilizedtitaniumoxo-acetate.So CNTscanbeusedasareliablematerialforenvironmentalpollutionclearingand canbeusedtoimprovethephotocatalyticefficiencyoftitania.
1.4.5Titania:ActivatedCarbonSemiconductorDoped PhotocatalysisSystem
Someresearchesupondopinganadditionalsemiconductoroveroutersurfaceoftitania:activatedcarbonincludeSnO2 ,V2 O5 ,ZnO,ZrO2 ,andCsS(Liaoetal. 2004). Theentireofitconfirmsthesuperiorphotodegradationefficiencyascomparedto thetitania:AC.Recentresearcheshavereportedthemodificationoftitania:activatedcarbonbysemiconductordopingthathasledtotheimprovementonremoval ofspecificcontainmentsinthegasresultinginthechangesofthephysicaland chemicalpropertiesofthecarbonmaterials.Iron(Fe3 O4 )dopanttitania:activated carbonhasbeenfoundasapromotertophotocatalysiswithagoodperformance ondegradationofcongoredandmethylorange.Someresearchershavecombined theFe3 O4 compoundwithtitania:activatedcarbonwithaimingatpreparingphotocatalysissubstratewithmagneticcoreandphotoactiveencapsulation.Theyproved thathybridsystemshadmagneticpropertiesandcouldbeseparatedbymagnetic materials.Itpointsoutthatthemagnetichybridphotocatalysissystemcanalsobe magneticallydisturbedbyadiscontinuousmagneticfieldinaninterruptedsystem, butfoundthatthephotocatalyticactivityofthehybridsystemdeclinedbecausethe magneticparticlesexperiencedthelightdissolution(Aoetal. 2008).
1.4.6Titania:ActivatedCarbonNonmetalDoped PhotocatalysisSystem
Dopingofnonmetal,suchasN,P,B,C,S,F,chlorine,andbromine,hasbeen alsowidelyusedtoimprovethephotocatalyticortoextendthephoto-absorption intovisiblelightoftitania:activatedcarbonsystem.Amongthem,theP-dopedtitania:activatedcarbonhasrecentlyattractedincreasinginterestduetoitsenhanced littlebandgap.Ithasanadsorptionpropertyinthevisiblelightregion,andalso foundthatphosphorous-dopedtitania:activatedcarbonpreparedbythebuffersolutionmethodwithNaH2 PO4 asprecursorshowedagreaterphotocatalyticactivityof acetaldehydeorganicburningundervisiblelightabsencethanthepuresample.It
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the exercise you need, if you walk five miles or more a day Golf, then, is really beneficial, and it costs you about $25.00 a week the year round.
So much for our “five major sports.” We look on at four of them, and if we can support the family, and pay taxes and insurance, on $1250 a year less than we earn, we take part in the fifth.
The minor sports, as the editor will tell you, are tennis, boating, polo, track athletics, trap-shooting, archery, hockey, soccer, and so on. Not to mention games like poker, bridge, bowling, billiards, and pool (now officially known as “pocket billiards” because the Ladies’ Guild thought “pool” must have something to do with betting), which we may dismiss as being of doubtful physical benefit, since they are all played indoors and in a fog of Camel smoke.
Of the outdoor “minors,” tennis is unquestionably the most popular. And it is one whale of a game—if you can stand it. But what percentage of grown-ups play it? I have no statistics at hand, and must guess. The number of adult persons with whom I am acquainted, intimately or casually, is possibly two thousand. I can think of ten who play as many as five sets of tennis a year.
How many of the two thousand play polo or have ever played polo? One. How many are trap-shooters? Two. How many have boats? Six or seven. How many run footraces or jump? None. How many are archers? None. How many play hockey, soccer, la crosse? None.
If I felt like indulging in a game of cricket, which God forbid, whom should I call up and invite to join me?
Now, how many of my two thousand acquaintances are occasional or habitual spectators at baseball games, football games, boxing matches, or horse races? All but three or four. The people I know (I do not include ball-players, boxers, and wrestlers, who make their living from sport) are average people; they are the people you know. And the overwhelming majority of them don’t play
Why not? If regular participation in a more or less interesting outdoor game is going to lengthen our lives, why don’t we
participate? Is it because we haven’t time? It takes just as much time to look on, and we do that. Is it because we can’t afford it? We can play tennis for as little as it costs to go to the bail-game and infinitely less than it costs to go to the races.
We don’t play because (1) we lack imagination, and because (2) we are a nation of hero-worshippers.
When we were kids, the nurse and the minister taught us that, if we weren’t good, our next stop would be hell. But, to us, there was no chance of the train’s starting for seventy years. And we couldn’t visualize an infernal excursion that far off. It was too vague to be scary. We kept right on swiping the old man’s cigars and giggling in the choir. If they had said that misdemeanours such as those would spell death and eternal fire, not when we were old, but to-morrow, most of us would have respected father’s property rights and sat through the service with a sour pan. If the family doctor were to tell us now that unless we got outdoors and exercised every afternoon this week, we should die next Tuesday before lunch, you can bet we should get outdoors and exercise every afternoon this week. But when he tells us that, without healthful outdoor sport, we shall die in 1945 instead of 1949, why, it doesn’t mean anything. It’s a chimera, a myth, like the next war.
But hero-worship is the national disease that does most to keep the grandstands full and the playgrounds empty. To hell with those four extra years of life, if they are going to cut in on our afternoon at the Polo Grounds, where, in blissful asininity, we may feast our eyes on the swarthy Champion of Swat, shouting now and then in an excess of anile idolatry, “Come on, you Babe. Come on, you Baby Doll!” And if an hour of tennis is going to make us late at the Garden, perhaps keep us out of our ringside seats, so close to Dempsey’s corner that (O bounteous God!) a drop of the divine perspiration may splash our undeserving snout—Hang up, liver! You’re on a busy wire!
R W. L
I. AS AN ENGLISHMAN SEES IT
A LITTLE less than two years ago—on the 14 July, 1919, to be exact—it fell to my lot, as an officer attached to one of the many military missions in Paris, to “assist,” from a reserved seat in a balcony of the Hotel Astoria, at the défilé, or triumphal entry of the Allied troops into Paris.
The march à Berlin not having eventuated owing to the upset in schedule brought about by the entry of dispassionate allies at the eleventh hour, it was felt that the French must be offered something in exchange, and this took the happy form of a sort of community march along the route once desecrated by Prussian hoof-beats—a vast military corbeille of the allied contingents, with flags, drums, trumpets, and all the rest of the paraphernalia that had been kept in cold storage during four years of gas, shell, and barbed wire. Such a défilé, it was calculated, would be something more than a frugal gratification to the French army and people. It would offer to the world at large, through the medium of a now unmuzzled press, a striking object lesson in allied good feeling and similarity of aims.
My purpose in referring to the défilé is merely to record one unrehearsed incident in it but I would say in passing that the affair, “for an affair,” as the French say, was extraordinarily well stage-managed. A particularly happy thought was the marshalling of the allied contingents by alphabetical order. This not only obviated any international pique on what we all wanted to be France’s day, but left the lead of the procession where everybody, in the rapture of delivery, was well content it should remain. Handled with a little tact, the alphabet had once more justified itself as an impartial guide:
B is for Britain, Great.
A is for America, United States of.
For impressiveness I frankly and freely allot the palm to what it was the fashion then to term the American effort. Different contingents were impressive in different ways. The Republican Guard, jack-booted, with buckskin breeches, gleaming helmets, flowing crinières, and sabres au clair, lent just the right subtle touch of the épopée of Austerlitz and Jena to make us feel 1871 had been an evil dream; the Highlanders, the voice of the hydra squalling and clanging from their immemorial pipes, stirred all sorts of atavistic impulses and memories. Nevertheless, had I been present that day in Paris as a newspaper man instead of as the humblest and most obscure of soldiers, neither one nor the other would have misled my journalistic instinct. I should have put the lead of my “story” where alphabetical skill had put the lead of the procession—in the American infantry.
In front the generalissimo, martial and urbane, on a bright coated horse that pranced, curvetted, “passaged” from side to side under a practised hand. At his back the band, its monster uncurved horns of brass blaring out the Broadway air before which “over there” the walls of pacifism had toppled into dust in a day. Behind them, platoon by platoon, the clean shaved, physically perfect fighting youth of the great republic. All six feet high—there was not one, it was whispered, but had earned his place in the contingent by a rigorous physical selection: moving with the alignment of pistons in some deadly machine—they had been drilled, we were told, intensively for a month back. In spotless khaki, varnished trench helmets, spick and span, scarcely touched by the withering breath of war. Whenever the procession was checked, platoon after platoon moved on to the regulation distance and marked time. When it resumed, they opened out link by link with the same almost inhuman precision, and resumed their portentous progress. How others saw them you shall hear, but to me they were no mere thousand fighting men; rather the head of a vast battering ram, the simple threat of which, aimed at the over-taxed heart of the German Empire, had ended war. A French planton of the Astoria staff, who had edged his way into the ticketed group was at my back. “Les voilà qui les attendaient,” he almost whispered. “Look what was waiting for them.”
The next balcony to mine had been reserved for the civil employés of British missions, and here was gathered a little knot of average English men and women—stenographers, typists, clerks, cogs of commercialism pressed into the mechanical work of post-war
settlement. As the Americans moved on after one of the impressive checks of which I have just spoken, something caught my ears that made me turn my head quickly, even from a spectacle every lost moment of which I grudged. It was, of all sounds that come from the human heart, the lowest and the most ominous—the sound that makes the unwary walker through tropical long grass look swiftly round his feet and take a firmer grasp on the stick he has been wise enough to carry.
It is impossible—it is inconceivable—and it’s true. On this great day of international congratulation, one of the two branches of the AngloSaxon race was hissing the other.
I spoke about the matter later to a friend and former chief, whom I liked but whose position and character were no guarantee of tact or good judgment. I said I thought it rather an ominous incident, but he refused to be “rattled.” With that British imperturbability which Americans have noted and filed on the card index of their impressions he dismissed the whole thing as of slight import.
“Very natural, I dare say. Fine show all the same. Perhaps your friends on the other balcony thought they were slopping over in front.”
“‘Slopping over...?’”
“Well—going a little too far Efficiency and all that. Bit out of step with the rest of the procession.”
I have often wondered since whether this homely phrase, uttered by a simple soldier man, did not come nearer to the root of the divergence between British and American character than all the mystifying and laborious estimates which nine out of ten of our great or near-great writers seem to think is due at a certain period in their popularity.
To achieve discord, you see, it is not necessary that two instruments should play different tunes. It is quite sufficient that the tempo of one should differ from the tempo of the other. All I want to indicate in the brief space which the scope of this work, leaves at my disposal are just a few of the conjunctures at which I think the beat of
the national heart, here and across the Atlantic, is likely to find itself out of accord.
Englishmen do not emigrate to the United States in any large numbers, and it is many years since their arrival contributed anything but an insignificant racial element to the “melting pot.” They do not come partly because their own Colonies offer a superior attraction, and partly because British labour is now aware that the economic stress is fiercer in the larger country and the material rewards proportionately no greater. Those who still come, come as a rule prepared to take executive positions, or as specialists in their several lines. Their unwillingness to assume American citizenship is notorious, and I think significant; but it is only within quite recent years that it has been made any ground of accusation—and among the class with which their activities bring them into closest contact it is, or was until a year or two ago, tacitly and tactfully ignored. During a review of the “foreign element” in Boston to which I was assigned two years before the war, I found business men of British birth not only reluctant to yield “copy” but resentful of the publicity to which the enterprise of my journal was subjecting them.
There are many reasons why eminent English writers and publicists are of little value in arriving at an estimate of “how Americans strike an Englishman.” While not asserting anything so crude as that commercial motives are felt as a restraining force when the temptation arises to pass adverse judgment on the things they see and hear, it is evident that the conditions under which they come—men of achievement in their own country accredited to men of achievement here—keep them isolated from much that is restless, unstable, but vitally significant in American life. None of them, so far as I know, have had the courage or the enterprise to come to America, unheralded and anonymous, and to pay with a few months of economic struggle for an estimate that might have real value.
To this lack of real contact between the masses in America and Great Britain is due the intrinsic falsity of the language in which the racial bond is celebrated on the occasions when some political crisis calls for its reiteration. It is felt easier and safer to utter it in consecrated
clichés—to refer to the specific gravity of blood and water, or the philological roots of the medium used by Milton and Arthur Brisbane. The banality, the insincerity, of the public utterances at the time that America’s entry into the European struggle first loomed as a possible solution of the agony on the Western Front was almost unbelievable. Any one who cares to turn up the files of the great dailies between September, 1916, and March, 1918, may find them for himself.
To a mind not clouded by the will to believe, this constant invocation of common aims, this perpetual tug at the bond to ensure that it has not parted overnight, would be strong corroboration of a suspicion that the two vessels were drifting apart, borne on currents that flow in different directions. It is not upon the after-dinner banalities of wealthy and class-conscious “pilgrims” nor the sonorous platitudes of discredited laggards on the political scene, still less is it upon the sporting proclivities of titled hoydens and hawbucks to whom American sweat and dollars have arrived in a revivifying stream, that we shall have to rely should the cable really part and the two great vessels of State grope for one another on a dark and uncharted sea. It is upon the sheer and unassisted fact of how American and Englishman like or dislike one another.
It is a truism almost too stale to restate that we are standing to-day on the threshold of great changes. What is not so well realized is that many of these changes have already taken place. The passing of gold in shipment after shipment from the Eastern to the Western side of the Atlantic and the feverish hunt for new and untapped sources of exploitation are only the outward signs of a profound European impoverishment in which Britain for the first time in her history has been called upon to bear her full share. The strikes and lock-outs that have followed the peace in such rapid succession might possibly be written off as inevitable sequelæ of a great war. The feeble response to the call for production as a means of salvation, the general change in the English temper faced with its heavy task are far more vital and significant matters. They seem to mark a shift in moral values—a change in the faith by which nations, each in the sphere that character and circumstance allot, wax and flourish.
Confronted with inevitable competition by a nation more populous, more cohesive, and richer than itself, it seems to me that there are
three courses which the older section of the English race may elect to follow. One is war, before the forces grow too disparate, and on the day that war is declared one phase of our civilization will end. It will really not matter much, to the world at large, who wins an Anglo-American world conflict. The second, which is being preached in and out of season by our politicians and publicists, who seldom, however, dare to speak their full thought, is a girding up of the national loins, a renewed consecration to the gospel of effort, a curtailment, if necessary—though this is up to now only vaguely hinted—of political liberties bestowed in easier and less strenuous days. The third course may easily be guessed. It is a persistence in proclivities, always latent as I believe in the English temperament, but which have only revealed themselves openly since the great war, a clearer questioning of values till now held as unimpeachable, a readier ear to the muttering and murmuring of the masses in Continental Europe, internationalism—revolution. No thoughtful man in England to-day denies the danger. Even references to that saving factor, the “common sense of the British workman,” no longer allays the spectre of a problem the issues of which have only to be stated to stand forth in all their hopeless irreconcilability. Years ago, long before the shadow fell on the world, in a moment of depression or inspiration, I wrote that cravings were stirring in the human heart on the very eve of the day when the call would be to sacrifice. That is the riddle, nakedly stated, to which workers and rulers alike are asked to find an answer to-day.
In this choice that lies before the British worker a great deal may depend upon how American experiments and American achievements strike him. In England now there is no escaping from the big transatlantic sister. Politicians use her example as a justification; employers hold up her achievements as a reproach. A British premier dare not face the House of Commons on an “Irish night” unequipped with artful analogies culled from the history of the war of secession. The number of bricks per hour America’s bricklayers will lay or the tons of coal per week her stolid colliers will hew are the despair of the contractor face to face with the loafing and pleasure-loving native born. You will hear no more jokes to-day in high coalition places over her political machine replacing regularly and without the litter and disorder of a general election tweedledum Democrat by a tweedledee Republican. She is recognized—and this, I think, is the final value
placed upon her by the entire ruling and possessing classes in my own country—as better equipped in her institutions, her character, and her population for the big economic struggle that is ahead of us.
This is the secret of the unceasing court paid to Washington by all countries, but pre-eminently by Britain. It is not fear of her power, nor hunger for her money bags and harvests, nor desire to be “on the band-wagon,” as light-hearted cartoonists see it, that prompts the nervous susceptibility and the instantaneous response to anything that will offend those in high places on the banks of the Potomac. It is the sense, among all men with a strong interest in maintaining the present economic order, that the support in their own countries is crumbling under their hands, and that that fresh support, stronger and surer, is to be found in a new country with a simpler faith and a cleaner, or at any rate a shorter, record. To fight proletarianism with democracy is a method so obvious and safe that one only wonders its discovery had to wait upon to-day. Its salient characteristic is a newly aroused interest and enthusiasm in one country for the political forces that seem to make stability their watchword in the other. The coalition has become the hero of the New York Times and Tribune—the triumph of the Republican party was hailed almost as a national victory in the London Times and Birmingham Post. Intransigeance in foreign policies finds ready forgiveness in London; in return, a blind eye is turned to schemes of territorial aggrandisement at Washington.
If a flaw is to be discerned in what at first sight seems a perfectly adjusted instrument for international comity, it is that this new AngloAmerican understanding seems to be founded on class rather than on national sympathy. Even offhand some inherent inconsistency would seem to be sensed from the fact that the appeal of the great republic comes most home, in the parent country, to the class that is least attached to democratic forms and the most fearful of change. References to America arouse no enthusiasm at meetings of the labour element in England, and it is still felt unwise to expose the Union Jack to possible humiliation in parades on a large scale in New York or Chicago. A sympathy that flowers into rhetoric at commercial banquets or at meetings of the archæologically inclined may have its roots in the soundest political wisdom. But to infer from such demonstrations of class solidarity any national community of thought or aim is both unwarranted and unsafe. This much is evident, that should a class
subversion, always possible in a country the political fluidity of which is great, leave the destinies of Great Britain in the hands of the class that is silent or hostile to-day when the name of America is mentioned, an entire re-statement of Anglo-American unity would become necessary, in terms palatable to the average Englishman.
This average Englishman is a highly complicated being. Through the overlay which industrialism has imposed on him, he has preserved to quite an extraordinary extent the asperities, the generosities, the occasional eccentricities of the days when he was a free man in a free land. No melting process has ever subdued the sharp bright hues of his individuality into the universal, all-pervading drab that is the result of blending primary colours. No man who has employed him to useful purpose has ever succeeded in reducing his personality to the proportions of a number on a brass tag. The pirate and rover who looked upon Roman villadom and found it not good, the archer who brought the steel-clad hierarchy of France toppling from their blooded horses at Crécy and Agincourt, the churl who struck off the heads of lawyers in Westminster Palace yard survive in him.
If I am stressing this kink in the British character it is because one of its results has been to make the Englishman of all men the least impressed by scale, and the one to whom appeals made on the size of an experiment or the vastness of a vision will evoke the least response, and especially because I think I perceive a tendency to approach him in the interests of Anglo-American unity precisely from the angle that will awake antagonism where co-operation is sought. The attachment of the Englishman to little things and to hidden things, which no one except Chesterton has had the insight to perceive, or at all events which Chesterton was the first to place in its full relation to his inconsistencies, explains his strangely detached attitude to that British Empire of which his country is the core. Its discovery as an entity calling for a special quality in thought and action dates no further back than that strange interlude in history, when the personality of Roosevelt and the vision of Kipling held the imagination of the world.
This refusal to be impressed by greatness, whether his own or others’, has its disadvantages, but at least it has one saving element. It
leaves an Englishman quite capable of perceiving that it is possible for a thing to be grandiose in scale and mean in quality. It leaves intact his frank and childlike confidence that the little things of the world confound the strong; his implicit conviction that David will always floor Goliath, and that Jack’s is the destined sword to smite off the giant’s head. The grotesqueness of the Kaiser’s upturned moustaches, the inadequacy of a mythical “William the Weed” to achieve results that would count, were his guiding lights to victory, the touchstones by which he tested in advance the vast machine that finally cracked and broke under its own weight. It was the “contemptible” little army of shopmen and colliers which seized his imagination and held his affection throughout, not the efficient mechanical naval machine that fought one great sea battle, which was a revelation of the risks inherent in its own monstrousness and complexity, and made its headquarters in Scapa Flow. I recall the comments heard at the time of Jutland in the artillery camp where fate had throwm me. They served to confirm a dawning conviction that the navy, while it still awes and impresses, lost its hold on the British heart the day wooden walls were exchanged for iron and steel. It is perhaps the “silent service” to-day because its appeal awakes so little response. It has been specialized and magnified out of the average Englishman’s power to love it.
In America the contrary seems the case. The American heart appears to go out to bulk, to scale, and to efficiency. The American has neither the time nor the temperament to test and weigh. His affections, even his loyalties, seem to be at the mercy of aspects that impose and impress. I know no other country where the word “big” is used so constantly as a token of affection. Every community has its “Big Tims,” “Big Bills,” “Big Jacks,” great hearty fellows who gambol and spout on public occasions with the abandonment of a school of whales. Gargantuan “Babe Ruth,” mountainous Jack Dempsey are the idols of its sport-loving crowds. “Mammoth in character,” the qualification which on the lips of the late Mr. Morgan Richards stirred laughter throughout England, is to the American no inconsequential or slipshod phrase. He does perceive a character and justification in bigness. It was perhaps to this trait in his mental make-up that the puzzling shift of allegiance to the beginning of the great war was due. The scale and completeness of the German effort laid hold of his imagination to an extent that only those who spent the first few months of agonizing doubt in the West
and the Middle West can appreciate. Something that was obscurely akin, something that transcended racial affinities and antipathies, awoke in him at the steady ordered flow of the field-grey legions Westward, so adequately pictured for him by Richard Harding Davis. He is quite merciless to defeat.
Nothing conceived on such a scale can indulge complexities. Its ideals must be ample, rugged, and primitive, adequate to the vast task. Hence the velocity, the thoroughness, the apparent ruthlessness with which American enterprises are put through. It is the fashion among a certain school of thought to call America the country of inhibitions. But there is little inhibition to be perceived on that side of his temperament, which the American has chosen to cultivate, leaving all else to those who find perverse attraction in weed and ruin. His language—and he is amazingly vocal—is as simple and direct as his thought. The appeals and admonitions of his leaders reverberate from vast and resonant lungs. They are calculated rather to carry far than to penetrate deeply. They are statements and re-statements rather than arguments. If their verbiage often aims at and sometimes seems to attain the sublime, if the American leader is forever dedicating, consecrating, inspiring something, the altitude is like the elevation given a shell in order that it may travel further. The nimble presentation of antithesis of a Lloyd George, the dagger-play of sarcasm of an Asquith, are conspicuously absent from the speeches of American leaders. There is something arrogant and ominous, like the clenching of a fist before the arm is raised, in this sonorous presentation of a faith already securely rooted in the hearts of all its hearers.
This primitiveness and single-mindedness of the American seem to intensify as his historical origins recede further and further into the past. It is idle to speculate on what might have happened had the development of his country remained normal and homogeneous, as, up to the Civil War, it admittedly did. It is an even less grateful task to look back on the literature of the Transcendental period and register all that American thought seems to have lost since in subtlety and essential catholicity. What is really important is to realize that not only the language but the essence of Occidental civilization has called for simplification, for sacrifice, year by year. It is hard to see what other choice has lain before the American, as wave after wave of immigration diluted his homogeneity, than to put his concepts into terms easily
understood and quickly grasped, with the philological economy of the traveller’s pocket manual and the categorical precision of the drill book. If in the very nature of things, this evangel is oftener pointed with a threat than made palatable with the honey of reason and sympathy, the task and not the taskmaster is to blame. On no other country has ever been imposed similar drudgery on a similar scale. It is idle to talk about the spiritual contribution of the foreigner when his first duty is to cast that contribution into the discard. It is futile to appeal to his traditions where the barrier of language rears itself in a few years between parents who have never learnt the new tongue and children who are unable or ashamed to speak the old.
But such a régime cannot endure for many years without a profound influence, not only on those to whom it is prescribed, but on those who administer it. The most heaven-born leader of men, put into a receiving depot to which monthly and fortnightly contingents of bemused recruits arrive, quickly deteriorates into something like a glorified and commissioned drill sergeant. The schoolmaster is notoriously a social failure in circles where intercourse must be held on the level to which the elevation of his estrade has dishabituated him. Exact values—visions, to use a word that misuse has made hateful— disappear under a multiplicity of minor tasks. It is one of the revenges taken by fate that those who must harass and drive become harassed and sterile in turn.
No one yet, so far as I know, has sought to place this amazing simplification in its true relation to the aridity of American life, an aridity so marked that it creates a positive thirst for softer and milder civilizations, not only in the foreigner who has tasted of them, but at a certain moment in their life in almost every one of the native born whose work lies outside the realm of material production. It is not that in England, as in every community, entire classes do not exist who seek material success by the limitation of interests and the retrenchment of sympathies. But in so doing they sacrifice to a domestic, not a national God; they follow personal not racial proclivities. There is no conscious subscription to a national ideal in their abandonment of æsthetic impulses. Side by side with them live other men whose apparent contentment with insecure and unstable lives at once redresses their pride and curtails their influence. They are conscious of the existence around them of a whole alien world, the material returns from which are
negligible but in which other men somehow manage to achieve a fullness of experience and maintain self-respect. This other world reacts not only on employer but on employed. For the worker it abates the fervour and stress of his task, lends meaning and justification to his demand for leisure in the face of economic demands that threaten or deny. No one in England has yet dared to erect into an evangel the obvious truth that poor men must work. No compulsion sets the mental attitude a man may choose when faced with his task. The speeder-up and the efficiency expert is hateful and alien. “A fair day’s wage for a fair day’s work” may seem a loose and questionable phrase, but its implications go very deep. It sets a boundary mark on the frontier between flesh and spirit by which encroachments are registered as they occur.
In America no such frontier exists. Here the invasion seems to be complete. The spirit that would disentangle material from immaterial aims wanders baffled and perplexed through a maze of loftily conceived phrases and exhortations each one of which holds the promise of rescue from the drudgery of visionless life, yet each one of which leads back to an altar where production is enthroned as God. Manuals and primers, one had almost written psalters, pour out from the printing presses in which such words as “inspiration,” “dedication,” “consecration” urge American youth not to the renunciation of material aims but to their intensive pursuit. This naïve and simple creed is quite free of self-consciousness or hypocrisy. In its occasional abrupt transitions from the language of prayer to such conscience-searching questions as “Could you hold down a $100.00 a week job?” or “Would you hire yourself?” no lapse from the sublime to the ridiculous, far less to the squalid, is felt. It has the childlike gravity and reverence of all religions that are held in the heart.
But its God is a jealous God. No faltering in his service, no divided allegiance is permitted. His rewards are concrete and his punishments can be overwhelming. For open rebellion, outlawry; for secret revolt, contempt and misunderstanding are his inevitable visitations. For this reason those who escape into heresy not unfrequently lose their integrity and are gibbeted or pilloried for the edification of the faithful. The man who will not serve because the service starves and stunts his soul is all too likely to find himself dependent for company upon the
man who will not serve because his will is too weak or his habits too dissipated.
That this service is a hard one, its most ardent advocates make no attempt to conceal. Its very stringency is made the text of appeals for ever and ever fresh efficiency, intensive training, specialization. “The pace they must travel is so swift,” one advocate of strenuousness warns his disciples, “competition has become so fierce that brains and vision are not enough. One must have the punch to put things through.” The impression grows that the American business man, new style, is a sombre gladiator, equipped for his struggle by rigorous physical and mental discipline. The impression is helped by a host of axioms, plain and pictured, that feature a sort of new cant of virility. “Red-blooded men,” “Two-fisted men,” “Men who do things,” “Get-there fellows,” are a few headliners in this gospel of push and shove.
The service is made still more difficult by its uncertainty, since no gospel of efficiency can greatly change the proportion of rewards, though it can make the contest harder and the marking higher. Year in year out, while competition intensifies and resources are fenced off, insecurity of employment remains, an evil tradition from days when opportunity was really boundless and competition could be escaped by a move of a few score miles Westward. Continuity in one employment still remains the exception rather than the rule, and when death or retirement reveals an instance it is still thought worthy of space in local journals. “Can you use me?” remains the customary gambit for the seeker after employment. The contempt of a settled prospect, of routine work, the conception of business as something to work up rather than to work at is still latent in the imagination of atavistic and ambitious young America. Of late years this restlessness, even though in so worthy a cause as “getting on,” has been felt as a hindrance to full efficiency, and the happy idea has been conceived of applying the adventurous element of competition at home. Territorial or departmental spheres are allotted within or without the “concern” to each employé; the results attained by A, B, and C are then totalled, analyzed, charted, and posted in conspicuous places where all may see, admire, and take warning. In the majority of up-to-date houses “suggestions” for the expansion or improvement of the business are not only welcomed but expected, and the employé who does not produce them in reasonable bulk and quality is slated for the “discard.” When inventiveness tires,
