酚試劑分光光度法測室內(nèi)甲醛

酚試劑分光光度法測定室內(nèi)甲醛實驗報告班級：130223學號：13022103姓名：董子薇1、ExperimentpurposeDeterminationofformaldehydeconcentrationinair,masterphenolreagentspectrophotometricmethodformeasuringformaldehyde；Learntoconfiguretheammoniumsulfate,phenolreagent,calibrationofformaldehydeandotherskills;Learntousespectrophotometer。2、ExperimentprinciplePhenol1、ExperimentpurposeDeterminationofformaldehydeconcentrationinair,masterphenolreagentspectrophotometricmethodformeasuringformaldehyde；Learntoconfiguretheammoniumsulfate,phenolreagent,calibrationofformaldehydeandotherskills;Learntousespectrophotometer。2、ExperimentprinciplePhenolreagent,chemicalnameforhydrochloricacid-3-methyl-2-benzothiazoleketonehydrazone,molecularformulaforC6H4SN(CH3)CNNH2,HCl,referredtoasandformaldehydecondensationreaction(phenolreagentastheformaldehydeabsorbent,chromogenicreagent)canMBTH.phenolreagent.Themethodwhenthesamplingvolumeto10L.Determinationofconcentrationlimitthescopefor0.01mg/m3~0.015,mg/m3)Formaldehydeinpurewaterisveryunstable,wheninthe0.005%phenolreagentcanbestabilizedby20h,itisusedforthepreparationofadilutesolutionofformaldehydestandardsolutioncontaining0.005%phenolreagentFormaldehydeandphenolreagentintheairtoproduce(A),theoxide(B)inacidicsolutionbyhighironionoxidationtoformabluegreencompound,colordepthandformaldehydecontentTheamountisproportionaltotheratioofthecolor:Note:phenolreagentisexcessive,theapartoftheabsorptionofformaldehydeCH322二NH+CH3+H2°(A)嗪(A)+(B)Fe3+[O][O]NHN=CH3NH-N藍綠色化合物HofintermediateB,aandBoccur1:1quantitativeadditionreaction,theformationofthebluegreensecondcondensationofformaldehyde-3-2-methylbenzothiazolehydrazone.Astheoxidantammoniumferricsulfateinthereactionisexcessiveandoxidationreactionandadditionreactionneedacertainamountoftime.Thisiswhyphenolformaldehydeabsorption.Afteraddingammoniumferricsulfatetowait15minutesaftertheredetermination.3、TestreagentInthismethod,thewaterusedinthismethodisheavydistilledwaterordeionizedwater,andthepurityofthereagentisgenerallyanalyzed.Theabsorptionsolution:weighing0.05gphenolreagent,dissolvedinwater,leanstoa50mlvolumetricflask,addingdeionizedwatertoscale.Placedintherefrigeratortosave,stablethreedays;phenolsolutionconcentration0.001g/ml)Theabsorptionliquid:amountofabsorptionsolutionof5mL,95mLanddeionizedwater.Whensamplingprowithfreshlyprepared(phenolsolutionconcentration;5X10、g/ml,i.e.0.005%)1%Ammoniumsulfatesolution:weigh1.0gammoniumsulfate[NH4Fe(SO4)2-12H2O]with0.1mol/LHClsolution(maximumabsorptionpeakpositionfor0.1mol/L,),anddilutedto100mL;(i.e.1%,0.01g/ml)formaldehydestandardreservingsolution:desirablecontentof0.28mL36%~38%formaldehydesolutionintoalitervolumetricflask,adddistilledwatertodilutescale,thissolution1mlequivalenttoabout1mgofformaldehyde.Theaccurateconcentrationiodinequantitymethodcalibration:Theexactamountofformaldehydestandardreservingsolution20.00mL,placedin250mlflaskiodine,and20mL0.5mol/Lofiodinesolutionofand15mL1mol/Lsodiumhydroxidesolution,placed15min,join20mL0.5mol/Lsulfuricacidsolution,thenplaced15min,with0.05mol/Lsodiumthiosulfatesolutiontitrationtopaleyellow,add1mlof0.5%starchsolution,totitratetothebluejustfaded,recordingconsumptionvolumeV,andwaterasthereagentblanktitration.Reactionprinciple:formaldehydesolution,alkalisolutionisalkaline,addingacertainamountofexcessiodinestandardsolution,formaldehydeisoxidized:HCHO+I2+3NaOH=HCOONa+2NaI+2H2OAfter15minutes,thereactionwascomplete,withsulfuricacid,starchasanindicator,withNa2S2O3standardsolutiontitrationexcessI2:I2+2Na2S2O3=2NaI+Na2S4O6V-V)xMx15Presstype(*)calculatedconcentration:C=—12^^:Checoncentrationofformaldehydeintheformaldehydestandardstocksolution,mg/ml;V1-thevolumeofsodiumsaltsolutionintheblank,ml;V2-thevolumeofsodiumsodiumsulfatesolutioninthetitrationofformaldehydesolution,ml;M-theequivalentconcentrationofsodiumsodiumsulfatestandardsolution;15-theequivalentofformaldehyde.20-thevolumeofthestandardstoragesolutionfortheformaldehyde,ml.VolumeV2(ML)ofsodiumandsodiumsulfatesolution5.2ThevolumeV1(mforthesolutionoftheblanksolutionwasconsumedbysodiuml)19.7Formaldehydesolutionconcentration(mg/ml)1.108Theerrorislessthan0.05mlandtheerrorislessthan,otherwiseitisre-calibration.(5)Formaldehydestandardsolution:Temporaryuse,fromthesolutionofformaldehydestandardstandbyremove0.9mlsolution,pronetoa100mlvolumetricflask,constantvolumetoscaleline;immediatelyretakingthesolution10.00ml,add100mlvolumetricflask,add5mlabsorptionliquidandwaterto100ml(thisonemilliliterofbloodinsolutioncontaining1001gformaldehyde),30minisplacedforpreparationofstandardcolortubes(thestandardsolution(standard)canbestablefor24hours).(5)Reagentsusedabove：①Iodinesolutionc1/2I2=0.010mol/L.iodineinstocksolutionandC1/2I2=0.1mol/L:weigh1.27giodine(i2)inthebeaker,add4gramsofpotassiumiodideanddeionizedwaterandstiruntilcompletelydissolved,dilutewithwaterto100ml,storageinbrownfinemouthbottle,darkstorage.Iodinesolutionc(1/2I2)=0.010mol/L:measurediodinereserveliquid25ml,dilutewithwaterto250ml,storageinthebrownvolumetricflask.@1mol/Lsodiumhydroxidesolution:weigh4Gsodiumhydroxide,solubleinwater,diluteto100mL；0.5mol/LSulfuricacidsolution:2.8mLconcentratedsulfuricacidslowlyaddedtothewater,coolingafterdilutionto100mL;Standardsolutionofpotassiumiodate[C1/6KIO3=0.1000mol/L]:accurateweighing0.35667gafterdryingatatemperatureof105DEGCfor2hoursofpotassiumiodate(top-gradepure),dissolvedinwater,movedtoa100mlvolumetricflask,andthenwaterwilldissolveto100ml.0.1mol/Lhydrochloricacidsolution:theamountof0.82mlconcentratedhydrochloricaciddilutedto100ml.Thestandardsodiumthiosulfatesolutionc(Na2S2O3)=0.1000mol/L:preparationmethod:thestandbysodiumthiosulfatesolution,C(Na2S2O3)=0.10mol/L:said25.0sodiumthiosulfate(Na2S2O3,5H2O)dissolvedin1000mlfreshlyboiledandcooledwater,0.20ganhydroussodiumcarbonateandstorageinbrownfinemouthbottleplacedaweekafterthecalibrationoftheconcentration,ifthesolutionappearmuddy.Afterfiltration.Aftercalibrationmethod:draw0.1000mol/Lpotassiumiodatesolution25.00mL,placedina250mlflaskiodine,75mlnewboiledandcooledwaterand3Gpotassiumiodide,andshaketodissolvecompletely,with0.1mol/LHClsolution10ml,immediatelycoverthebottleandshake.Inthedarkplace3min,0.10mol/Lsodiumthiosulfatereservesolutiontitrationtopaleyellow,addstarchsolution1ml,continuetotitratetothebluejustfaded,recordthevolumeVoftheconsumptionofsodiumthiosulfatereservesolution,presstype(**)concentrationsareCWaSO)=°.1000*I。.。。calculated:223V(**):C(Na2S2O3)—theconcentrationofsodiumthiosulfatestoragesolution,mol/L;V-thevolumeofthesodiumsaltsolutionwasconsumedbytitration,ml.Thedifferenceofthevolumeofthesodiumandsodiumsulfatesolutionusedintheparalleltitrationshouldnotexceedthe0.05ml.orre-calibration.oSodiumstandardsolutionofsodiumsaltC(Na2S203)=0.1000mol/L：Aftercalibration,the0.1mol/Lsodiumthiosulfatereservesolution50ml,placedin500mlvolumetricflask,boilingandcoolingwaterdilutedtomarking,shake,storageinbrownfinemouthbottle.Titrationofsodiumandsodiumsulfatesolutionvolume(ML)24.5Theconcentrationofsodiumthiosulfatesolution(mol/L)standby0.102Fifthly,0.5%starchsolution:0.5gofsolublestarch,withasmallamountofwater,tuneintoapaste,thenadd100mlofboilingwater,andbringtotheboil2~3mintotransparentsolution.Aftercooling,adding0.1gofsalicylicacidor0.4gzincchloridepreservation;4、instrumentthelargebubbleabsorptiontube:theoutletdiameteris1mm,theairoutletpipetothebottomdistanceisequaltoorlessthan5mm;spectrophotometricdeterminationofabsorbanceat630nm;constantcurrentsampler:flowrange0-1L/min;(stabilityoftheflowcanbeadjusted,constantcurrenterrorislessthan2%,usesoapmembraneflowmetercalibrationsamplerflowsamplingbeforeandaftersampling,theerrorshouldbelessthan5%.plugtube:10mL;4、Sampling1.standard；ThenationalstandardofChinanationalstandardofformaldehydeintheindoorairmg/(GB/T16127-1995):thehighestallowableconcentrationofformaldehydeintheairof0.08cubicmeters.Thesamplingtimeofthephenolreagentspectrophotometricmethod(GB/T18024.26-2000)isalargebubbleabsorptiontubewithaninner5mlabsorptionliquid,10L,L/min,20min.,andrecordthesamplingpointsoftemperatureandatmosphericpressure(sampleatroomtemperatureshouldbeanalyzedwithin24h).2.drawingstandardcurve:10mLcolorcomparisontubes,accordingtotable1toprepareastandardseries.1formaldehydestandardseriesTubenumberStandardworkingfluid/ml［機］absorptionliquid/mlFormaldehydecontent/g00.05.000.0010.104.900.1020.204.800.2030.404.600.4040.604.400.6050.804.200.8061.004.001.0071.503.501.5082.003.002.005、AnalyticalprocedureAftersampling,5mlofsamplesolutionfullytransferredto10mlthancolortube,toeachtubeadded0.4ml1%ammoniumferricsulfatesolution,shake,roomtemperaturecolor30minutes.With10mmcuvettes,atawavelengthof630nm,withwaterasreference(notsampling5mlofabsorptionliquidreagentblank).Withformaldehydecontentastheabscissaabsorbanceforthelongitudinalcoordinates,curvedrawingandcalculationregressionslopeandtothereciprocaloftheslopeasasampleforthedeterminationofcalculationfactorBG(micrograms/absorbance).Aftersampling,thesamplesolutionwastransferredintothecolortube,withasmallamountofabsorptionliquidabsorptiontube,combinedtomakethetotalvolumeof5ml,add0.4mlammoniumsulfatesolution,color15min.determinationofabsorbance(A),atthesametime,using5mlnottosampletheabsorptionsolutionasthereagentblank,thereagentblankabsorbance(A0).7、ResultsreliabilityanalysisStandardworkingcurveFormaldehydecontent/g/5ml0.0000.600.80Formaldehydecontent/g/5ml0.0000.600.801.502.00AbsorbanceFormaldehydecontent/g/5ml0.0000.0170.0530.1380.2040.2900.5390.721Absorbance甲醛含量測定標準工作曲線0.800六、結果計算1.將采樣體積寫B(tài)/T18883-20IV。——換字成——蓉——采樣體積示4T0.800六、結果計算1.將采樣體積寫B(tài)/T18883-20IV?！獡Q字成——蓉——采樣體積示4T0T—標準狀態(tài)下的絕對溫度273K；|T一一采樣點氣溫，@.;50P?！獦藴薁顟B(tài)下的大氣壓，101.3kPa;P——采樣點的大氣壓，kPa。甲醛含量換算成標準狀態(tài)下的采樣體積：02：—V0=V-Tj（273+t）：標準狀態(tài)下的喪一一，,V=采樣流量（L/min）X采樣時間（min）;體積，L；1.001.502.002.50=0.3669x-0.0116R2=0.9992*吸光度—線性（吸光度）測試養(yǎng)點甲醛含量Formaldehydeconcentration以g/5mlAbs0.07100.0160.34500.117Uc0.024508085StandarddeviationStandarderrorS0.71StandarddeviationStandarderrorS0.00788Sxx0.366949Cvaluetobemeasured0.345C=0.3450X10^~^/10=0.00345mg/m3<0.08mg/m31.Resultsreliabilityanalysis:Therelativeuncertaintyurel(V0)isintroducedintothesamplevolume;Theflowofthesamplerisintroducedtherelativeuncertaintyofurel(Q),QC-1Samplerflowerrorislessthan5%,accordingtotherectangulardistribution,k=3;urel(Q)=5%/V3=0.0289;Relu(T)forthetimesetwhenthesampleisfixed.QC-1typegassamplingtimeerrorislessthan1%,accordingtotherectangulardistribution,k=3,urel(T)=1%/V3=0.0057;Therelativeuncertaintyofurel(T)wasintroducedbythethermometer.-10~100degreescentigradethermometeratmosphericerrorisabout1DEGC,accordingtotherectangulardistribution,k=3,urel(T)=1/V3/(273+25)=0.0019;Insummary,thesamplingvolumeisintroducedandtherelativeuncertaintyofurel(V0)=V(0.02892+0.00572+0.00192)=0.0295Theuncertaintyoftheintroductionof10g/LMformaldehydestandardsolutionisintroduced.Urel(standard)CapacitybottlecausedbythestandarduncertaintyThestandardsolutionvolumebottle100LM(Agrade),itsrelativestandarduncertaintyof0.000577(NationalTechnicalSupervisionBureau)UncertaintyofstandardsolutionofsodiumsaltBythecertificateofstandardsolution,intermsofrectangulardistributioncalculation,standarduncertaintyis0.00015/V3=0.000087.Therelativestandarduncertaintyis:0.000087/0.1099=0.000792.UncertaintyofformaldehydestandardsolutionThevolumetricerrorofthetwoparalleltitrationis0.03lm,thevolumeofthecalibrationsolutionisabout20lm,whichcanbecalculatedbytriangulardistribution,thestandarduncertaintyofthecalibrationis0.003/6=0.012,therelativestandarduncertaintyis:0.012/20=0.00061.Synthesisoftheforegoingcomponentstostandardsolutionpreparationcausedatotalofrelativesta