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119963JOURNALOFINORGANICCHEMISTRYVol.12,No.1March,1996XÌ(,,210093)(SiO2öNa2O),,2,:,[1],,,,,[2,3],1(Na2SiO39H2O),,,;(315,),NaOH,,SiO2Na2O(SiO2,Na2O),210310pHS23;300151pH[2],:(1),(SiO2öNa2O)110210310;(2),110210310HOAcH2SO4lgt()2pHNlgtTs(HOAc,NaOAc;H2SO4,Na2SO4),,,lgtX:19952042153,(028000):,,39,,:1[3]:logt=logC-2logTa+log(1+B1[H+]+B2[H+]2+B3[H+]3)2B2B3[H+]3-log(B1öB3+[H+]2)(1)1Fig.1Gellingcurveofmonosilicicacidgelationagent:HOAcconstantconcentrationofsalt:0.480molL-1NaOActemperature:30concentrationofmonosilicicacid(molL-1):(1)0.085;(2)0.120;(3)0.170;(4)0.240t,TaB1=1öK2,B2=1öK2K1,B3=1öK2K1K0,K2K1K0H3SiO-4,H4SiO4H5SiO+4,[H3SiO-4]=[H5SiO+4],H4SiO4,[H4SiO4]öTa1(1)A=1ö2(pK1-pK0)-lg2pK1pK0,A,,lgt-AlgTa[2(a)],lgt-AlgTa,1(1),-2,1-2,lgt-AlgTa[2(b)],-2(1)(1),,,lgt-AlgTs(Ts),lgt-AlgTs[2(c)],11,lgt-AlgTa1lgt-AlgT(TaTs)Table1Slopeofthelgt-AvslgT(TaorTs)attheMaximumPointofMonosilicicAcidGelationCurvegelationagentinconstantsaltconcentrationconstantsaltconcentrationconstantsilicicacidconcentrationHOAc-3.52-2.06-1.30H2SO4-4.55-1.96-2.7210112lgt-AlgT(TaTs)Fig.2Relationshipbetweenlgt-AandlgT(TaorTs)atthemaximumpointsofN2curvesa)inconstantconcentrationofsalt;T-totalconcentrationofsilicicacid(Ta)b)constantconcentrationofsalt;T-totalconcentrationofsilicicacid(Ta)c)inconstantconcentrationofsilicicacid;T-totalsaltconcentration(Ts)gelationagent:o-HOAc;-H2SO41,,,[H4SiO4]=[H3SiO-4],,[H4SiO4]öTa[H3SiO-4]öTa1ö2,(1)2lg2,lgt-2lg2lgTa,,2,,,-2,2lgt-2lg2lgT(TaTs)Table2Slopeofthelgt-2lg2vslgT(TaorTs)attheMinimumPointofMonosilicicAcidGelationCurvegelationagentinconstantsaltconcentrationconstantsaltconcentrationconstantsilicicacidconcentrationHOAc-3.10-2.04-1.14H2SO4-3.06-2.09-1.00210310,,34,-23lgt-AlgTaTable3Slopeofthelgt-AvslgTaattheMaximumPointofMultisilicicAcidGelationCurvewithConstantSaltConcentrationSiO2öNa2Ogelationagentslope2.0HOAc-2.16H2SO4-2.133.0HOAc-2.03H2SO4-2.19201124lgt-2lg2lgTaTable4Slopeofthelgt-2lg2vslgTaattheMinimumPointofMultisilicicAcidGelationCurvewithConstantSaltConcentrationSiO2öNa2Ogelationagentslope2.0HOAc-2.12H2SO4-2.043.0HOAc-2.13H2SO4-2.19,,,[4][5],,,[1]Iler,R.K.,TheChemistryofSilica,JohnWiley&Sons,(1979)1[2],,23,98(1957)1[3],1979,É182,(1980)1[4],,5(6),769(1984)1[5],,1(2),31(1980)1VERIFICATIONFORORDEROFPOLYMERIZATIONREACTIONOFSILICICACIDLiRuiyanWangJinxiChenYuehuaChenRongsanDaiAnbang(CoordinationChemistryInstitute,StateKeyLaboratoryofCoordinationChemistry,NanjingUniversity,Nanjing210093)GelationratesofacidifiedsodiumsilicatesolutionwithdifferentSiO2öNa2Oratiowerestudiedbythemethodofgelationcurve.Itwasfoundthattherateconstantofthegelationwas2intheconstantconcentrationofsalt.Thisfindingwasinagreementwithmechanismofpolymerizationofsilicicacidwhichwehadproposed.Keywords:sodiumsilicategelationraterateconstant3011