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1、FuelVol.76,No.12,pp.1085-1090,1997©1997ElsevierScienceLtd.AllrightsreservedPrintedinGreatBritainPII:S0016-2361(97)00126-90016-2361/97$17.00+0.00ELSEVIERThecationexchangepropertiesoftheheat-treatedAustralianbrowncoalinthewater-organiccompoundsmixedsolutionsKenjiMurakamia'*,TakahikoYa
2、madaa,KiyoshiFudaa,ToshiakiMatsunagaaandYoshiyukiNishiyamabaDepartmentofMaterialsEngineeringandAppliedChemistry,MiningCollege,AkitaUniversity,Akita010,JapanblnstituteforChemicalReactionScience,TohokuUniversity,Sendal980-77,Japan(Received13January1997)Thedistributionofacidstrengthofc
3、arboxylgroupsinrawandheat-treatedAustralianLoyYangbrowncoalswasestimatedbythesodiumtitrationmethod.Theacidityofrawcoalvarieswidely.Thetotalamountofcarboxylgroupsforheat-treatedcoalsisreducedbythermaldecomposition,butthedistributionoftheaciditybarelychanges.Also,theinteractionbetween
4、surfacefunctionalgroupsofbrowncoalandmetalcationswasexaminedbycationexchangeexperiments.Forallcations,theextentofcationexchange(ECE)oftherawcoalincreasedwithpH,whichsuggeststhattheECEforrawcoaliscontrolledmainlybytheaciddissociationequilibriumofcarboxylgroups.Formagnesiumandcobaltio
5、ns,theECE'sofheattreatedcoalsweresmallerthanthoseestimatedfromthermaldecompositionofthecarboxylgroups.Incontast,theECE'sinwater-organicmixedsolutionwerelargerthanthoseinaqueoussolution.ECE'sincreasedlinearlywithswellingofcoalcausedbyadditionoforganiccompounds.Thegradientofthisincrea
6、sewaslargerforcobaltthanformagnesiumandalsotheslopeforsamplestreatedathighertemperaturesormeasuredathigherpHlevels.Theseresultsarediscussedintermsofthechangeoftheporesizedistributionbytheheattreatmentofthecoalaswellasswellingofcoalbyadditionoforganiccompoundswhichcausesachangeinthec
7、ationaccessibilitytothecarboxylgroups.Fromtheseresults,thevariationofthemacromolecularnetworkstructureisconsideredtobeanimportantfactorforthecationexchangepropertiesofbrowncoalinadditiontochemicalfactors,suchasaciddissociationequilibrium.©1997ElsevierScienceLtd.(Keywords:Australianb
8、rowncoals;ionexchan
