A study of anti-corrosion behavior of Imidazoline

第十三届全国缓蚀剂学术讨论会论文集460Astudyofanti-corrosionbehaviorofImidazolinederivative-treatedmildsteelYUPing*,LUOYun-baiCollegeofChemistryandMolecularScience,WuhanUniversity,Wuhan430072,ChinaAbstract：Animidazolinederivative(OED)wassynthesizedinlaboratory.Itsthermaldiscomposedtemperaturewasconfirmedbydifferencethermalanalysis(DTA).TheinvestigationoftheinhibitionperformanceofOEDformildsteelinalkalineenvironmenthasbeencarriedout.Theoptimumconditionsoftheanti-corrosionbehavioroftheOED–treatedmildsteelsamplewereestablishedusingacidityCuSO4droppingtestandcontactanglemeasurement.ThebestprotectiveOEDfilmwasformedonthesurfaceafterthemildsteelsamplesweretreatedinsteamat280°Cinanautoclavefor2hours,usingasolutionOEDconcentrationof40mg/L,pH9.6.Fouriertransforminfrared(FTIR)andX-rayphotoelectronspectroscopy(XPS)wereusedtocharacterizethesurfacefilm.FTIRresultsrevealedtheOEDmodifiedthephysicalstructureofthemildsteellayer.FromXPSanalysis,itisbelievedthatthesurfacelayersoftheOEDtreatedsampleconsistedofironoxideswithNfillinitsdisfigurements.KeyWords：Imidazolinederivation;anti-corrosion;mildsteel;FTIR;XPS1.IntroductionThecorrosionofmildsteelinthermalpowerequipmentisaproblemforpowercompanieswhensuchequipmentistemporarilyshutdownformaintenanceorotherpurpose,asthewaterinsidetheequipmentcouldnotbecompletelyremoved.Thecorrosionproductscouldadverselyaffecttheoperationand,hence,thecostofthethermalpowerequipment.Itwasfoundthetreatmentswithorganicnitrogencompoundshadsubstantiallypreventedorminimizedthecorrosioninthermalpowerequipment[1-6].Imidizolinederivation(OED),[RCN2(CH2)2CH3CH2CH2OH]CH3SO4],hasbeensynthesizedinourlaboratory,andexperimentswereshownthatitwasaneffectivecorrosioninhibitorformildsteel,andhasbeenusedinthermalpowerindustriesandpetroleumindustries[7,8].However,theanti-corrosionactionsofthesurfaceprotectivefilmsarestillnotwellunderstood.Thepresentworkestablishedtheconditionunder*Correspondingauthor.Address:CollegeofChemistryandMolecularScience,WuhanUniversity,Wuhan430072,China.Tel:[phone];fax:[phone];E-mailaddress:[e-mail]-corrosionbehaviorofImidazolinederivative-treatedmildsteel461whichoptimalanti-corrosionbehavioroftheOED-treatedmildsteelsampleswereachieved,andprovidesaninsightonthesurfaceprotectivefilms.2.MaterialandmethodsTheimidazolinederivative(OED)wassynthesizedinthelaboratory.ThecompositionofmildsteelisC0.17-0.24;Si0.17-0.37;Mn0.35-0.65;P0.04;S0.04;Cr0.25;Ni0.25;Febalance.Thesampleswerepolishedwithdifferentgradesofemerypapers(#180,#300,#600,#800)andthenwashedanddegreasedwithalcohol.Theywerethendriedandrinsedwithdeionizedwater,finallydriedatroomtemperature.ThesesampleswithfreshlypreparedsurfacewerethentheOED-treatedinanautoclaveinthefollowingmanner:0.5literofde-ionizedwaterwithaknowconcentrationOED.ThepHadjustedto9.4-9.6withNH4OHsolution.Itwasaddedtotheautoclave,andthesystemwasthepurgedwithN2gasfor30min.Theautoclavewasthenheateduptoaspecificliquidphasetemperatureandmaintainedatthattemperaturefortwohours.Thepoweroftheautoclavewasthenturnedoffandtheautoclavewasallowedtocooltotheroomtemperature.TheOED–treatedmildsteelsampleswerethenremoval,andusedotherexperiments.Differencethermalanalysis(DTA)wasanalyzedbythermalanalysisinstrument(DT-30B,Japan).Cruciblewasmadeofplatinum.Temperatureincreased10°C/minduringroomtemperatureto400°Caroundnitrogen.AcidityCuSO4droppingtestwasperformedinsamplesfilmsurfacewithmixedsolution(0.4mol/LCuSO440mL+10%NaCl20mL+0.1mol/LHCl15mL).Becausemixsolutionhascorrosiontosamplefilmsurfaceandthefilmwasdestroyedwhenitwasdroppingonthesample.Thechemicalreactiontookplace:Cu2++Fe=Cu+Fe2+.Thefilmcolor(blue)waschangedfrombluetored(copper).Thelongerofthechangingtimewas,thebetteroftheanti-corrosionandthemoreuniformityofthefilm.Thecontactanglewasdeterminedonthemildsteeldiskcoatedwiththefilmbythesessiledropmethodusingamicroscopicgoniometer.Themeasurementwascarriedoutonthediskwithadropof15mm3waterundertheambientatmosphere.Severalrunsofthemeasurementwererepeatedatdifferentplacesonthediskandtheaveragevaluewasdetermined.Fouriertransforminfrared(FTIR)measurementswererecordedusing170sxFT-IRNicolet,(USA)spectrometer.X-rayphotoelectronspectroscopy(XPS)wascarriedoutusingXSAM800KRATOS(Japan)onsmallsample(7×7×1mm),employinganexcitationsourceofMgKaradiation(1253.6eV)operatedat12.5Kvand16mA.Surveyandhighresolutionspectrawereobtainedwiththeanalyserpassenergysetat1to800eV,theywererecordedtodeterminetheconstitutivespecialinterest第十三届全国缓蚀剂学术讨论会论文集462wereperformedforcertainenergies(Fe,N,OandC,).ComputerdeconvolutionwasperformedbystripingwithsputteringgunwithAr+,at6.4kVand10Macm-1,sputteringdepthprofileanalysiswereconductedtodeterminethechangeinconcentrationofeachelementatdifferentdepthsinthesurfacefilm.3.SynthesisAnimidazolinederivativewaspreparedfromoleicacid,N-(2–hydroxyethyl)ethylenediamineanddimethylsulfate,followedbydehydrolysisundervacuumandchangedintodaisychain.Thendimethylsulfatewasaddedtothesolution.Itssynthesizerouteasfollowing:CH3(CH2)7CHCH(CH2)7COOHNH2CH2CH2NHCH2CH2OHHO+2CH3(CH2)7CHCH(