沉淀与结晶相结合实现水软化汪翠萍

　　　200927沉淀与结晶相结合实现水软化汪翠萍　宋存义　孙大均　李霞(,　100083)　:结合传统沉淀技术和结晶技术,在碳酸钙自发成核和外加晶核条件下,以控制过饱和度的方式,进行水软化试验。经研究结果显示,自发成核条件下未发现晶体颗粒的生长;而在外加晶核条件下,晶体具有一定程度的生长,但不同SRT下晶体粒径之间的差异并不明显,其可能原因为反应时间较短,及晶核在循环过程中被破坏。:介稳区;沉淀;结晶;晶核;软化;SRTREALIZATIONOFWATERSOFTENINGBYINTEGRATINGPRECIPITATIONWITHCRYSTALLIZATIONWangCuiping　SongCunyi　SunDajun　LiXia(DepartmentofEnvironmentalEngineering,SchoolofCivilandEnvironmentalSciences,BeijingUniversityofScienceandTechnology,Beijing100083,China)Abstract:Byintegratingtheconventionalprecipitationwithcrystallization,itwascarriedoutthewatersoften-ingexperimentinthemethodofcontrollingsupersaturationundertheconditionsofauto-crystallizationandadditiveseedsrespectively.Duringtheauto-crystallization,itwasnotfoundthatthecrystalsgrewup;how-ever,CaCO3crystalsgrewupthroughaddingtheseed.ThedistinctionsbetweentheparticlesatdifferentSRTconditionsarenotapparentbecauseoftheexperimentequipmentortheshortexperimenttime.Keywords:Metastability;precipitation;crystallization;crystalseeds;softening;SRT0　。,20%[1]。,70%～80%[2]。。,。[3];,,,,,。1972,。,、、,、[4]。,,。,[5]。,。,,,。1　,,,,。90%,10%,,。。,。Niels-en[6-7],,,,。1975Lowitz。20DOI:10.13205/j.hjgc.2009.s1.113　　　200927[8-10]。NielsenAαBβ,1[9]。p(A)-lg[A]/(mol·L-1);p(B)-lg[B]/(mol·L-1)。1　AαBβ,,,、,[11]。,,。2　2。,210mm、240mm,LZB-4Qin=6L/h;Qc=1L/h,1‰NaOH。120mm、1000mm。1-;2-;3-;4-;5-;6-;7-。2　3　3.1　介稳区的确定pH=8.5、9.5。CaCl2Na2CO3。2h,CaCl2Na2CO3,;,,,。,p[Ca]T(=-lg[Ca]T)p[CO3]T(=-lg[CO3]T),34。3　(pH=8.5,T=25℃)4　(pH=9.5,T=25℃)34,,、,、。34,pH。,Ca2+CO32-,。3.2　碳酸钙自发成核试验,,“”:SRT=θ=X·VXw·Qw(1)　X———,mg/L;　V———,L;　Xw———,mg/L;　Qw———,L/d。21　　　200927,X=Xw,(1)(2):SRT=θ=VQw(2)　　,1,SRT=0.5,1,2d。,Ca2+64mg/L,NaOH,2,。SRTCa2+、pH56。5　SRT6　pHSRT56,SRT,pH9.8。,,,Ca2+CO32-,,,,。,,,。3.3　外加晶核成长试验:(n=300rpm)400mL0.5mol/LNa2CO3400mL0.5mol/LCaCl2,3min,90rpm。30min,,,400mL0.5mol/LNa2CO3,400mL0.5mol/LCaCl2,、、。,,3,。3μm。SRT=1,2,3d。TSS7。2SRT,SS,SRT=1,2,3d1060,2350,3170mg/L。pHCa2+9.86mg/L。SRT,89。7　TSS8,,。9,,,SRT。,:1),SS,,,,,CaCO3,。10,。2),,,,。　　3),,,Ca2+。22　　　2009278　SRT=1,2,3d(5000)9　SRT=1,2,3d(500)10　4　1),,。2),,,,。3),,,,SRT。[1],,.[J].,2003,32(8):9-11.[2],,.[J].(),2004,13(2):154-158.[3],,.[J].,2004;6:30-33.[4]WillardD,HarmsJ,RobinsonRB.Softeningbyfluidizedbedcrys-tallizers[J].JEnvironEng,1992,118(4):513-529.[5]ZhouP,HuangJ-C,WeiS.Heavymetalremovalfromwastewaterinfluidizedreactor[J].WatRes,1999,33(8):1918-1924.[6]ArneErikNielse,JensM.Toft.Electrolytecrystalgrowthkinetic[J].JournalofCrystalGrowth,1984,67:278-288.[7]ArneErikNielse.Electrolytecrystalgrowthmechanisms[J].Jour-nalofCrystalGrowth,1984,67:289-310.[8]NyvltJ,SohnetO.Thekineticsofindustrialcrystallization[M].Amsterdam:Elsevier,1985.[9]ReddyMM.Crystallizationofcalciumcarbonateinthepresenceoftraceconcentrationsofphosphateandions[J].J.CrystalGrowth,1977(41):287-295.[10]MullinJW.Solutionconcentrationandsupersaturationunitsandtheirconversionfactors[J].TheChemicalEngineer,1973,273:316.[11],.[J].,1986,12(4):21-35.　　100083　E-mail　[e-mail]2008-10-1623