carrygao41.com

PEER-REVIEWEDARTICLEbioresources.
comGaoetal.
(2011).
"ControlofStickiesinONPmill",BioResources6(2),1916-1925.
1916CONTROLOFSTICKYCONTAMINANTSWITHCATIONICTALCINDEINKEDPULPYangGao,a,b*MenghuaQin,aChaoLi,aHailongYu,aandFengshanZhangbInthisstudyacationictalcwasappliedtodeinkedpulpforcontrolofstickycontaminants.
Effectsofthecationictalconstickiesanddissolvedandcolloidsubstanceswereinvestigatedandcomparedwiththoseofaconventionaltalc.
Characteristicsofwet-endchemistrywereexaminedforthepulpwithadditionofbothkindsoftalcsamples.
Furthermore,influencesonpaperpropertieswerealsocompared.
TheresultsshowedthattheadditionofcationictalccaneffectivelydecreasethecontentofstickiesandDCS,whilereducingthecationicdemandofthepulp,andtheturbidityofthefiltrate.
Depositionofstickiescanbereducedbyabout63%withtheadditionof2.
0%cationictalcintothepulp,andtheDCSwasreducedfrom1989mg/Lto1927mg/L.
Additionofcationictalcsignificantlyincreasedtheashcontentofthepaper,butitnegativelyinfluencedthepaperstrengthproperties.
Keywords:Cationictalc;Deinkedpulp;Stickycontaminants;Stickiescontrol;PaperpropertiesContactinformation:a:KeyLaboratoryofPaperScienceandTechnologyofMinistryofEducation,ShandongPolytechnicUniversity,Ji'nan,Shandong,250353China;b:HuataiGroupCo.
Ltd.
,Guangrao,Shandong,257335China;*Correspondingauthor:y_gao@hotmail.
comINTRODUCTIONStickiesremainoneofthemajorobstaclesinthemanufactureofqualitynewsprintfromrecycledfibers.
Sourcesofstickiesmayincludeadhesives,hotmelts,coatingbinders,inkresidues,deinkingchemicals,rosin,andwetstrengthresin.
Inmillpractices,thecontaminantsremaininginthepulpfurnishcanbuildupwithinthepapermachineheadbox,ontheformingwire,inthepresssection,andinthedryersection,causingoperationproblemsandharmingproductquality(Hubbeetal.
2006;Blancoetal.
2007).
Controlofstickycontaminantsiscrucialforpapermakingwithdeinkedpulps.
Therefore,differentmeasureshavebeendevelopedandappliedinmillpractices(Dechandtetal.
2004).
Stickyparticles,especiallymicro-stickies,showaffinitytotalcs,andtheG(Gibbsfreeenergy)foradsorptiveadhesionbetweennaturaltalcandstickysubstancesisinrangeof-23to-42mJ/m2(Schweighofer2010).
Adsorptionofstickysubstanceswithadditionofcationicpolymersorcationictalcisoneofthereasonableapproachessothattheycanberetainedintheformedpapersheet(Wgbergetal.
1995;Biza2001).
Talcisahydratedmagnesiumsilicatewithalaminatedstructure.
Themineralhasanoctahedralbrucitelayersituatedbetweentwotetrahedralsheetsofsilica.
ItispresentedbythechemicalformulaofMg3(OH)2Si4O10.
Talcisnaturallyhydrophobic,sothatitcannotbewettedinwaterwithouttheuseofsurfactant.
Hydrophobicityisanapparentpropertyoftheplanarface,whiletheexposedparticleedgesarehydrophilicduetothepresenceofpH-influencedMgOH+groups(Charnayetal.
2001;Gueraetal.
2005).
PEER-REVIEWEDARTICLEbioresources.
comGaoetal.
(2011).
"ControlofStickiesinONPmill",BioResources6(2),1916-1925.
1917Talccanbecationizedbyadsorbingcationicpolymersattheedgesoftalcplatelets,duetoastronginteractionthatmayexistbetweenthepolymerandthehydroxylgroups.
Ifenoughcationicpolymersareadded,thenthenetsurfacechargeoftalccanbeconvertedfromnegativetopositive,whichisimportantforattractingstickyparticlesthatusuallycarrynegativecharges.
Furthermore,talcactsasfillerinapaperstructureandtrapstheanionictrashonitsmineralparticles,sothattheycanberemovedfromthepulpsuspension.
Inaddition,paperpropertiescanbebasicallymaintainedduetothefactthatthefibersurfaceremainsavailabletoperformitsprimaryfunctionforfiber-fiberbonding(Biza2001;Hayakawaetal.
2004;Morrisetal.
2002).
Theobjectiveofthisstudyistoinvestigatetheeffectivenessofcationictalcforthecontrolofstickycontaminantsindeinkedpulps,andtoexamineitsinfluencesonthewet-endchemistryofpulpsandpropertiesofpaperhandsheets.
Theinvestigationalsoincludesacomparisonwiththeresultsofadditionofconventionaltalc.
Itishopedthatthepreliminaryresultsobtainedfromthisinvestigationwillprovidesomeusefulinformationforthepapermillpracticewhichutilizesrecycledfibers.
EXPERIMENTALMaterialsThedeinkedpulpwassampledfromthemachinechestofacommercialdeinkingpulingline,andtheconventionaltalcwasobtainedfromthesamemill.
CationictalcwasprovidedbytheRioTintoMinerals.
MeasurementofStickyContaminantsTheadditionlevelsofbothkindsoftalcswerevariedas0%,0.
5%,1.
0%,1.
5%and2.
0%.
TheTAPPIstandardprocedurewasfollowedtoform120g/m2paperhandsheets,exceptthatasheetofaluminumfoilwasputontheformedpapersheetforthepurposeofmeasuringgravimetricallystickysubstances.
Thepapersheetwaspressedtogetherwiththealuminumfoil.
Thepapersheetwasdriedtogetherwiththealuminumfoilat130°Cfor10min.
Thealuminumfoilwasthenseparatedfromthepaper.
Weighingthealuminumfoil,theincreaseinweightisconsideredasthestickysubstances(Delagoutteetal.
2001).
Theaverageof12measureswastakenastheresult.
MeasurementofDissolvedandColloidSubstancesThepulpslurrywasfiltratedwithaDynamicDrainageJar(DDJ,100-meshscreen)toremovethefiberfractions.
Then50mLoffiltratewascentrifugedat2000rpm.
for20min.
toobtainthesupernatant,whichcontainingthedissolvedandcolloidsubstances(DCS).
Theaverageofthreemeasurementswastakenastheresult.
ExaminationofWet-endChemistryCharacteristicsThecationicdemandofthepulpwasdeterminedbypolyelectrolytetitrationwithaPCD-03MütekParticleChargeDetectorfromBTG,andpoly-diallyl-dimethyl-ammoniumchloride(PDADMAC)at0.
001mmoL/Lconcentrationwasusedasastandardcationicpolyelectrolyte.
TheturbidityoffiltratewasdeterminedwithaHachPEER-REVIEWEDARTICLEbioresources.
comGaoetal.
(2011).
"ControlofStickiesinONPmill",BioResources6(2),1916-1925.
19182100NTurbidityMeter.
Thezeta-potentialofpulpswasdeterminedwithaMütekSZP-04zeta-potentialtester.
MeasurementofPaperPropertiesThestrengthandopticalpropertiesofhandsheetsweretestedaccordingtotheChinesestandardmethodsofGB/T453-1989,GB/T455.
1-1989,andGB/T7974-2002.
AshcontentwasmeasuredaccordingtothemethodofGB/T463-1989.
ImagesoftalcsampleswereimagedwithaFEIQuanta200SEM.
RESULTSANDDISCUSSIONControlofStickieswithAdditionofTalcFigure1showsthattheamountofstickydepositsdecreasedwithadditionofbothkindsoftalcs.
Itiseasytounderstandthatthestickysubstancescanbeadsorbedorwrappedbytalcparticles,whichreducestheirtackiness,anditmakesthemeasiertoremaininapapersheet.
Therefore,thefreetackyparticles,i.
e.
amountofsubstancesexaminedbythealuminumfoilmethodwasdecreased,asshowninFig.
1.
0510152025300.
00.
51.
01.
52.
02.
5AdditionofTalc(%)StickyDeposits(mg)ConventionalTalcCationicTalcFig.
1.
AdditionoftalcversusstickydepositOnecanconcludethatthecationictalcshowedabetterperformanceforreducingstickydepositsthanthatofconventionaltalc.
Atthesameadditionlevelof2.
0%,thedepositswerereducedfrom16.
0mgto10.
6mgforaddingconventionaltalc,andto5.
9mgforaddingcationictalc,whichaccountedfor33.
8%and63.
1%,respectively.
Thisresultisunderstandablebasedonthefactthatthecationictalcparticleshadbeentreatedwithcationicpolymers,whichwouldbeexpectedtoremainadsorbedontheedgesoftalcparticles,sothattheycanbeusedmoreeffectivelytotrapstickysubstances.
PEER-REVIEWEDARTICLEbioresources.
comGaoetal.
(2011).
"ControlofStickiesinONPmill",BioResources6(2),1916-1925.
1919ControlofDCSwithAdditionofTalcFigure2showsthechangeofdissolvedandcolloidsubstanceswithadditionoftalcs.
ItcanbeseenthattheDCSinthefiltratewasreducedfrom1989mg/Lto1927mg/Latanadditionlevelof2%cationictalc;howevertheDCSresultswerenotsignificantlyaffectedbytheadditionofconventionaltalcoverthevariedadditionlevelsupto2%.
Apossibleexplanationisthatthechargebalanceinthepulpsystemchangedwithaddingofcationictalc,andsomeDCStherebylosttheirstability,sothattheywereeasilyagglomeratedwitheachother,andfinallytrappedbytalcparticles.
Apparently,adecreaseofDCSwillbebeneficialtotherecirculationofprocesswaterinapapermakingsystem.
16001700180019002000210022000.
00.
51.
01.
52.
0AdditionofTalc(%)DCS(mg/L)ConventionalTalcCationicTalcFig.
2.
AdditionoftalcversusDCScontentCharacteristicsofWet-endChemistryItisshowninFig.
3thatthezetapotentialofthepulpslightlydecreasedwiththeadditionofbothkindsoftalcs,especiallyinthecaseofthecationictalc(decreasedfromminus28.
5mVtominus29.
9mVatanadditionlevelof2.
0%).
Zetapotentialrepresentstheamountofsurfacechargesofpulpfibers.
Thisindicatesthatthestickysubstanceswereabsorbedontopulpfibers,whichcanaccountoftheincreaseofnegativechargeswithincreasingadditionlevelsoftalc.
Inadditiontoabsorbingstickyparticles,anionictrashcanalsobetrappedbythecationictalc,andthisledtofurtherdecreaseofzetapotential.
ItcanbeseeninFig.
4thatthecationicdemanddecreasedsignificantlywiththeadditionofbothkindsoftalcs.
Asdiscussedabove,stickyparticlescanbewrappedbythetalcparticles,leadingtothedecreaseofnegativechargesinthepulpsuspension.
Cationicdemandisfurtherdecreasedwithincreasingamountoftalcs,especiallyathigheradditionlevels.
Thecationictalcshowedahigherdecreaseofcationicdemand,whichcanbeexplainedbythepositivechargecarriedbythecationictalc.
Thismadeitattractivenotonlytostickiesbutalsotoanionicdissolvedandcolloidalsubstances.
PEER-REVIEWEDARTICLEbioresources.
comGaoetal.
(2011).
"ControlofStickiesinONPmill",BioResources6(2),1916-1925.
1920-34-32-30-28-26-240.
00.
51.
01.
52.
02.
5AdditionofTalc(%)ZetaPotential(mV)ConventionalTalcCationicTalcFig.
3.
Additionoftalcversuszetapotential2000220024002600280030000.
00.
51.
01.
52.
02.
5AdditionofTalc(%)CationicDemand(eq/L)ConventionalTalcCationicTalcFig.
4.
AdditionoftalcversuscationicdemandTheresultsshowninFig.
5indicatethattheturbidityincreasedslightlywithadditionofconventionaltalc,butitdecreasednoticeablywiththeadditionofcationictalc.
Thisisnotunreasonable,sinceinthecaseofaddingconventionaltalc,sometalc-stickiescomplexesmaypassthroughthescreenoftheDDJapparatusandremaininthefiltrate,whichresultsinahigherturbidity.
Forthecaseofaddingofcationictalc,morestickysubstancesareattracted,andattachedontopulpfibers.
Thissubsequentlyleadstolesssuspendedparticulatesinthefiltrate,i.
e.
showingasalowerturbidity.
Inaddition,thecationicchargescarriedbytalcscanalsocausethecolloidsubstancestobecomeaggregated,sothattheturbidityisfurtherdecreased.
PEER-REVIEWEDARTICLEbioresources.
comGaoetal.
(2011).
"ControlofStickiesinONPmill",BioResources6(2),1916-1925.
1921020040060080010001200140016000.
00.
51.
01.
52.
02.
5AdditionofTalc(%)Turbidity(NTU)ConventionalTalcCationicTalcFig.
5.
AdditionoftalcversusturbiditySEMImagesofTalcsRetentionoftalcparticlesinapapersheetisrelatednotonlytothesurfacechargesbutalsotothecharacteristicsofthetalc.
ThemorphologiesoftalcsampleswereobservedwithaSEM.
TheimageswereacquiredandasshowninFigs.
6and7.
Itcanbeseenthattheconventionaltalcexhibitedinalaminatedstructure.
Asreportedintheliterature(Charnayetal.
2001),anoctahedralbrucitelayerissituatedbetweentwotetrahedrallayersofsilica;becausetheyarecombinedmainlybytheVandeWaalsforce,theyaremoreeasilyseparatedintolamellaeorevensmallerpiecesThecationictalcshowedascale-likeormicrocrystallinestructure,andwithalargespecificsurfacearea.
Therefore,itdemonstratedahigherabsorptiontendencywheninteractedwithstickyparticlesandcolloidsubstances.
Fig.
6.
SEMimageofcationictalcPEER-REVIEWEDARTICLEbioresources.
comGaoetal.
(2011).
"ControlofStickiesinONPmill",BioResources6(2),1916-1925.
1922Fig.
7.
SEMimageofconventionaltalcEffectofAddingTalconPaperPropertiesFigures8and9showthatthepapertensileandtearindexesdecreasedwiththeadditionofbothkindsoftalc.
Itisclearthatasinorganicmaterials,additionoftalcnoticeablyaffectedthefiber-fiberbonding.
Asshowninthefigures,addingcationictalcresultedinahigherdecrementofpaperstrength.
Asdiscussedpreviously,thecationictalctrappedmorestickycontaminantsthandidtheconventionaltalc,sothatitaffectedtoalargerextenttothefiber-fiberbonding.
Thissuggeststhatinamillpracticeofaddingtalc,acombinationshouldbeconsideredtoachievecontrolofstickycontaminants,whilealsomaintainingthedesiredpaperstrengthproperties.
202530354045500.
00.
51.
01.
52.
02.
5AdditionofTalc(%)TensileIndex(N.
m/g)ConventionalTalcCationicTalcFig.
8.
AdditionoftalcversustensileindexPEER-REVIEWEDARTICLEbioresources.
comGaoetal.
(2011).
"ControlofStickiesinONPmill",BioResources6(2),1916-1925.
19238.
09.
010.
011.
012.
00.
00.
51.
01.
52.
02.
5AdditionofTalc(%)TearIndex(mN.
m2/g)ConventionalTalcCationicTalcFig.
9.
AdditionoftalcversustearindexFigure10showsthedevelopmentofpaperbrightnesswithadditionofbothconventionalandcationictalcs.
Theconventionaltalcprovidedthepaperhandsheetswithahigherbrightnessthanthecationictalc.
Itiseasytounderstandthatthehigherbrightnessresultedfromthehigherbrightnessofconventionaltalc.
585960616263640.
00.
51.
01.
52.
02.
5AdditionofTalc(%)Brightness(%,ISO)ConventionalTalcCationicTalcFig.
10.
AdditionoftalcversusbrightnessAsexpected,theashcontentofthepaperincreasedwithadditionofbothkindsoftalc,asshowninFig.
11.
Comparedwiththeconventionaltalc,thepapersheetswithadditionofcationictalcwereobservedtohaveahigherashcontent.
Atadditionlevelof2.
0%,theashcontentincreasedfrom3.
3%to6.
2%foraddingcationictalc,equivalenttoanadditionlevelof5.
0%fortheconventionaltalc.
Thisindicatedthatthecationictalcshowedahigherretentionefficiency,whichwillbenefitthemilltosavecostlyfinematerialinthefurnish.
PEER-REVIEWEDARTICLEbioresources.
comGaoetal.
(2011).
"ControlofStickiesinONPmill",BioResources6(2),1916-1925.
19240246810120.
00.
51.
01.
52.
02.
5AdditionofTalc(%)Ash(%)ConventionalTalcCationicTalcFig.
11.
AdditionoftalcversusashcontentCONCLUSIONS1.
Additionofcationictalcshowedanapparentbenefitforthecontrolofstickiesanddissolvedandcolloidsubstances.
Measuredbythealuminumfoilmethod,about63%ofstickycontaminantscouldberemovedfromthedeinkedpulpwiththeadditionof2.
0%cationictalc.
2.
Theturbidityofthefiltrate,zetapotential,andcationicdemandofthepulpcanbesignificantlydecreasedbyaddingcationictalc.
Comparedtotheconventionaltalc,thecationictalcshoweddifferentmorphology,whichprovidedahigherspecificsurfacearea,inadditiontobetterabsorptionability.
3.
Addingcationictalcsignificantlyincreasedtheashcontentofthepaper,butshowednegativeeffectonpaperstrengthproperties.
Theadditionlevelshouldbeconsidered,combiningwiththedesiredpaperstrengthandcontrolofstickycontaminants.
ACKNOWLEDGMENTSTheauthorsaregratefulforthesupportofTaishanScholarProgram(TS200637022)bytheShandongProvinceGovernment,theNationalNaturalScienceFoundationofChina(GrantNo:30972327),andtheProgramforNewCenturyExcellentTalentsatUniversities(NCET-08-0882)forthisresearch.
WewouldalsoliketothankDr.
HongmeiWeiofRioTintoMineralforprovidingcationictalc.
PEER-REVIEWEDARTICLEbioresources.
comGaoetal.
(2011).
"ControlofStickiesinONPmill",BioResources6(2),1916-1925.
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Articlesubmitted:December20,2011;Revisedversionreceivedandaccepted:March8,2011;Published:April10,2011.