MAP沉淀法目标产物最优形成条件及分析方法郝晓地

MAP1,1,1,vanLoosdrechtMCM2(1.,　100044;2.Kluyver,Delft2628BC,):(MAP:MgNH4PO4·6H2O),,;NH+4-N().,pH(),pHCa2+.,MAP,XRD.,90%pH7.5～9.0,,pH7.0～7.5.Ca2+,(pH8.0)MAP.,,MAPpH(8.0).:;pH;Ca2+;XRD;;:X703　:A　:0250-3301(2009)04-1120-06:2008-05-21;:2008-07-14:(863)(2006AA06Z320);(BJE10016200611);(KM200910016009):(1960～),,,,,E-mail:[e-mail]　OptimalFormationConditionsandAnalyticalMethodsoftheTargetProductbyMAPPrecipitationHAOXiao-di1,LANLi1,WANGChong-chen1,vanLoosdrechtMCM2(1.Research&DevelopmentCentreofSustainableEnvironmentalBiotechnology,BeijingUniversityofCivilEngineeringandArchitecture,Beijing100044,China;2.DepartmentofBiochemicalEngineering,DelftUniversityofTechnology,Delft2628BC,Netherlands)Abstract:Inordertoestablishoptimalconditionsofthestruvite(MAP:MgNH4PO4·6H2O)formation,aciddissolutionwasappliedanddevelopedtoperformelementanalysesontheprecipitatesobtainedfromMAPprecipitation,andanovelanalyzingandcalculatingmethodwasdevelopedtoquantitativelydeterminethestruvitecontent(purity)intheharvestedprecipitatesaccordingtotheNH+4-Ncontent.Withthismethod,thepuritiesofstruvitewererespectivelydeterminedforbothultrapurewaterandtapwaterusedassolutes.Atthesametime,theeffectofpHandCa2+ontheformationandcrystallizationofstruvitewasevaluated.Thenewlydevelopedmethodwaseffectiveenoughtodeterminethepuritiesofstruvite,whichcouldbeabettermethodthanqualitativeX-raydiffraction(XRD).Basedonthedevelopedmethod,itwasfoundthattheoptimalpHrangesforhavingahighstruvitecontent(90%)wererespectivelyat7.5-9.0withultrapurewaterassoluteandat7.0-7.5withtapwaterassolute.Inrealwastewater,Ca2+atpH8.0mightresultinimpuritiesratherthanstruvite.Therefore,aneutralpHrange(8.0)isproposedtoperformstruviteprecipitationinwastewater.Keywords:struvite;pH;Ca2+;XRD;dissolutionmethod;elementanalyses　　,,(MAP:MgNH4PO4·6H2O).、、,[1～3]..,[1～7].、pH;LeCorre[8,9],Ca2+.X(XRD)[1,8～12]、(SEM-EDS)[8].,,XRD,XRD[1,8,10～12],().,XRD.,,,30420094　　　　　　ENVIRONMENTALSCIENCEVol.30,No.4Apr.,2009DOI:10.13227/j.hjkx.2009.04.027XRD.,,、.,,.,,,(Mg、NP)(1∶1∶1).,(90%)MAP.,Ca2+,Ca2+.1　1.1　NaH2PO4·2H2O、MgSO4·7H2O、NH4ClNaOH.(99.0%,Alfa-Aesar).1.2　,I0.5L5.0mmolNaH2PO4·2H2O;Ⅱ0.5L6.0mmolMgSO4·7H2O15.0mmolNH4Cl.Ⅱ1.5L,Ⅰ,.Mg∶N∶P1.2∶3∶1[13]..pH=6.5,NaOH(NaOH,1molLNaOH)0.5pH,pH,6.5～11.5.(25℃)30min,.,.、1h,.,,,(,).,(25℃).,.:c(Ca2+)=2.17mmolL,c(Mg2+)=1.34mmolL.1.3　X(RigakuDmaxIIIA),Zeiss(AxioCamMRc5).1.4　,,[14],.:40.00mg,(pH1),250mL.ICP-AES(IRISAdvantage)[15],(DX-120)Mg2+、Ca2+NH+4-N[16].2　2.1　XRD,Mg2+、NH+4-NPO3-4.,,pH,Boistelle[17]Schuiling[18].,HPO2-4PO3-4,:Mg2++NH+4+HPO2-4+6H2OMgNH4PO4·6H2O+H+(1)　　,pH、Ca2+.,pH(、)[1,6,9].,(25℃),,pH.2,XRD,(99.0%,Alfa-Aesar),1.1(),,pH7.5～9.0,XRD();,XRDpH7.0～8.5.XRD,pH,.1,pH,,.,pH9.0,XRD,,.11214:MAP1　pHXRDFig.1　XRDandmicroscopicimagesoftheprecipitatesformedinultrapurewaterandtapwaterwithdifferentpH1122　　　　　　30,,Mg(OH)2(Ksp=5.1×10-12)Mg3(PO4)2(Ksp=1.0×10-24)[19].pH,,,.,Ca2+,pHMg(OH)2Mg3(PO4)2,,Ca3(PO4)2(Ksp=2.1×10-33),CaHPO4(Ksp=1.8×10-7)[19]、Ca10(PO4)6(OH)2[20].1,,pH7.5～9.0,pH7.0～8.5.2,pH、().,pH.2.2　()(),..,:N(0.6456mmolL)、P(0.6464mmolL)Mg(0.6532mmolL),(N、P、Mg)(0.6520mmolL).,().,2,23.2　Fig.2　Elementanalysesofthedissolvedprecipitatesfromultrapurewater2,,pH≤10.5,pH,NH+4-N;pH10.5,NH+4-N.pH=11.0,pH.3　Fig.3　ElementanalysesofthedissolvedprecipitatesfromtapwaterNH+4-NNH3,(2).,NH+4-N,NH3,NH+4-NNH3、[21].,pH.,pH,NH+4-N,Mg3(PO4)2Mg(OH)2,Lee[22].NH+4+OH-NH3+H2O(2)　　3.pH,NH+4-N.pH≥10.5,NH+4-N,.pH≤8.5,Ca2+.,pH8.5,Ca2+,,Ca2+[Ca3(PO4)2、CaHPO4、Ca10(PO4)6(OH)2],,[8,20].,pH8.5,[Mg3(PO4)2Mg(OH)2].pH≥10.0,Ca2+PO3-4,.2.3　(1),N、P、Mg1∶1∶1.,pHCa2+,PMg.,N.,1molN1mol.,(3):=n×Mm×100%(3),n;M;m.11234:MAP(3),98.9%,(99.0%).,(3).(3)2,4.,pH7.510.5,,,90%pH7.5～9.0,pH10.5,.4,pH,Ca2+.pH7.07.5,96.8%95.7%.pH7.5,,pH=10.0,15.5%.pH10.0,.,Ca2+CaNH4PO4·7H2O[23].,NH+4-N.(3),,pH8.5Ca2+,CaNH4PO4·7H2O,.pH≤8.5Ca2+,(3).4　pHFig.4　ImpactofpHonthestruvitepurityintheprecipitates3　(1),,,XRD,.(2),NH+4-N.(3)pHCa2+,,90%pH7.5～9.0,,pH7.0～7.5.pH,Ca2+Ca2+,.(4)Ca2+,,pH8.0.(5)pH,,.,.:[1]　PastorL,ManginD,BaratR,etal.Apilot-scalestudyofstruviteprecipitationinastirredtankreactor:conditionsinfluencingtheprocess[J].BioresourTechnol,2008,99(14):6285-6291.[2]　RonteltapM,MaurerM,GujerW.Struviteprecipitationthermodynamicsinsource-separatedurine[J].WaterRes,2007,41:977-984.[3]　WilsenachJ,SchuurbiersC,vanLoosdrechtM.Phosphateandpotassiumrecoveryfromsourceseparatedurinethroughstruviteprecipitation[J].WaterRes,2007,41:458-466.[4]　,,vanLoosdrechtMCM.[J].,2006,53(3):191-198.[5]　OhlingerK,YoungT,SchroederE.Predictingstruviteformationindigestion[J].WaterRes,1998,26:2229-2232.[6]　AbbonaF,BoistelleR,LundagerH.Crystallizationoftwomagnesiumphosphates,struviteandnewberyite:effectofpHandconcentration[J].JCrystGrowth,1982,57:6-14.[7]　TaylorA,FrazierA,GurneyE.Solubilityproductsofmagnesiumammoniumphosphate[J].TransFaradaySoc,1963,59:1580-1584.[8]　LeCorreK,ValsamiJE,HobbsP,etal.Impactofcalciumonstruvitecrystalsize,shapeandpurity[J].JCrystGrowth,2005,283(3-4):514-522.[9]　StratfulI,ScrimshawM,LesterJ.Conditionsinfluencingtheprecipitationofmagnesiuma