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Microbial corrosion (MIC) yog ib qho teeb meem loj hauv ntau qhov kev lag luam vim nws tuaj yeem ua rau kev lag luam loj loj.2707 super duplex stainless hlau (2707 HDSS) tau siv nyob rau hauv marine ib puag ncig vim nws cov tshuaj tiv thaiv zoo heev.Txawm li cas los xij, nws qhov kev tiv thaiv rau MIC tsis tau sim ua pov thawj. Hauv qhov kev tshawb fawb no, MIC tus cwj pwm ntawm 2707 HDSS tau tshwm sim los ntawm cov kab mob marine . Electrochemical tsom xam pom tau hais tias nyob rau hauv lub xub ntiag ntawm Pseudomonas aeruginosa biofilm nyob rau hauv 2216E nruab nrab, muaj ib tug zoo hloov nyob rau hauv corrosion muaj peev xwm thiab ib tug nce nyob rau hauv corrosion tam sim no ceev.X-ray photoelectron spectroscopy (XPS) tsom xam pom ib tug txo nyob rau hauv Cr cov ntsiab lus nyob rau saum npoo ntawm cov qauv hauv qab lub biofilm pit pits qhia qhov siab tshaj plaws ntawm biofilm.Imaging pit. Qhov tob ntawm 0.69 μm thaum lub sij hawm 14 hnub ntawm incubation.Txawm hais tias qhov no me me, nws qhia tau hais tias 2707 HDSS tsis muaj zog tiv thaiv kab mob MIC ntawm P. aeruginosa biofilms.
Duplex stainless steels (DSS) yog dav siv nyob rau hauv ntau yam industries rau lawv zoo tagnrho ua ke ntawm zoo heev mechanical zog thiab corrosion resistance1,2.Txawm li cas los xij, localized pitting tseem tshwm sim thiab nws cuam tshuam rau kev ncaj ncees ntawm no steel3,4.DSS tsis resistant rau microbial corrosion (MIC) 5,6.Txawm hais tias muaj ntau yam ntawm daim ntaub ntawv ntawm DSS nrog cov khoom siv ntev ntev ntawm cov khoom siv corrosion tsis txaus. Kev tiv thaiv corrosion yuav tsum tau.Jeon et al7 pom tias txawm tias super duplex stainless hlau (SDSS) muaj qee qhov kev txwv ntawm kev tiv thaiv corrosion.Yog li ntawd, super duplex stainless hlau (HDSS) nrog kev tiv thaiv corrosion ntau dua yuav tsum muaj nyob rau hauv qee qhov kev siv.
Kev tiv thaiv corrosion ntawm DSS nyob ntawm qhov sib piv ntawm alpha thiab gamma theem thiab Cr, Mo thiab W depleted cheeb tsam 8, 9, 10 nyob ib sab rau theem ob.HDSS muaj cov ntsiab lus siab ntawm Cr, Mo thiab N11, yog li nws muaj kev tiv thaiv corrosion zoo heev thiab tus nqi siab (45-50) Pitting Resistance Equivalent Number (PREN. 0.0%) w + 0% w. W) + 16 wt% N12.Nws zoo heev corrosion kuj nyob ntawm qhov sib npaug sib npaug uas muaj kwv yees li 50% ferrite (α) thiab 50% austenite (γ) theem, HDSS muaj cov khoom siv kho tshuab zoo dua thiab siab dua li cov pa DSS13.Chloride corrosion zog.Qhov txhim kho corrosion kuj nthuav dav siv HDSS nyob rau hauv ntau corrosive chloride ib puag ncig, xws li marine ib puag ncig.
MICs yog ib qho teeb meem loj hauv ntau qhov kev lag luam xws li roj thiab roj thiab cov khoom siv dej 14.MIC nyiaj rau 20% ntawm tag nrho cov corrosion puas 15.MIC yog bioelectrochemical corrosion uas tuaj yeem pom nyob rau hauv ntau qhov chaw.Biofilms uas tsim rau ntawm cov hlau nto hloov cov electrochemical tej yam kev mob, yog li cuam tshuam cov txheej txheem corrosion. staining zog kom ciaj sia17.Cov kev tshawb fawb MIC tsis ntev los no tau qhia tias EET (extracellular electron hloov) yog tus nqi-txhim kho hauv MIC induced los ntawm electrogenic microorganisms.Zhang li al.18 pom tau hais tias electron mediators nrawm hloov hluav taws xob ntawm Desulfovibrio sessificans hlwb thiab 304 stainless hlau, ua rau MIC hnyav dua.Enning li al.19 thiab Venzlaff et al.20 tau pom tias cov kab mob corrosive sulfate-txo cov kab mob (SRB) biofilms tuaj yeem nqus cov hluav taws xob ncaj qha los ntawm cov hlau substrates, ua rau muaj qhov hnyav pitting corrosion.
DSS paub tias yuav raug rau MIC nyob rau hauv ib puag ncig uas muaj SRB, hlau-txo cov kab mob (IRB), thiab lwm yam.
Pseudomonas aeruginosa yog ib tug kab mob gram-negative motile rod-zoo li tus kab mob uas yog dav faib nyob rau hauv nature25.Pseudomonas aeruginosa kuj yog ib tug loj microbial pab pawg neeg nyob rau hauv marine ib puag ncig, ua rau MIC rau steel.Pseudomonas yog nyob ze rau cov txheej txheem corrosion thiab raug lees paub raws li ib tug pioneer colonation formalizer.28 and Yuan et al.29 pom tau hais tias Pseudomonas aeruginosa muaj ib qho kev nyiam ua kom muaj zog corrosion ntawm cov hlau me me thiab cov alloys nyob rau hauv ib puag ncig aqueous.
Lub hom phiaj tseem ceeb ntawm txoj haujlwm no yog txhawm rau tshawb xyuas MIC cov khoom ntawm 2707 HDSS tshwm sim los ntawm cov kab mob marine aerobic Pseudomonas aeruginosa siv cov txheej txheem electrochemical, cov txheej txheem kev soj ntsuam saum npoo thiab cov khoom siv corrosion.Electrochemical cov kev tshawb fawb suav nrog Qhib Circuit Court Potential (OCP), Linear Polarization Resistance (LPR), Electrochemical Potential Impedance (Electrochemical Potential Impedance) MIC tus cwj pwm ntawm 2707 HDSS.Energy dispersive spectrometer (EDS) tsom xam tau ua kom pom cov tshuaj lom neeg ntawm qhov chaw corroded. Ntxiv rau, kev tsom xam X-ray photoelectron spectroscopy (XPS) tau siv los txiav txim qhov kev ruaj ntseg ntawm oxide zaj duab xis passivation nyob rau hauv lub zog ntawm ib puag ncig marine muaj Pseudomonas SM aeruginosa.
Table 1 teev cov tshuaj muaj pes tsawg leeg ntawm 2707 HDSS.Table 2 qhia tau hais tias 2707 HDSS muaj cov khoom siv kho tshuab zoo heev nrog lub zog tawm los ntawm 650 MPa.Daim duab 1 qhia tau hais tias qhov kho qhov muag microstructure ntawm cov tshuaj tua hluav taws kub kho 2707 HDSS.Elongated bands ntawm austenite thiab ferrite theem 5 yuav pom nyob rau hauv cov theem 0 microstructure tsis muaj 0% microstructure. ferrite theem.
Daim duab 2a qhia tau hais tias qhib Circuit Court muaj peev xwm (Eocp) piv rau lub sij hawm raug cov ntaub ntawv rau 2707 HDSS nyob rau hauv abiotic 2216E nruab nrab thiab P. aeruginosa broth rau 14 hnub ntawm 37 ° C.Nws qhia tau hais tias qhov loj tshaj plaws thiab tseem ceeb kev hloov nyob rau hauv Eocp tshwm sim nyob rau hauv thawj 24 teev.Qhov Eocp qhov tseem ceeb nyob rau hauv ob qho tib si v . ly, ncav cuag -477 mV (vs. SCE) thiab -236 mV (vs. SCE) rau cov qauv abiotic thiab P, feem ).Pseudomonas aeruginosa daim coupon, ntsig txog.Tom qab 24 teev, Eocp tus nqi ntawm 2707 HDSS rau P. aeruginosa kuj tseem ruaj khov ntawm -228 mV (vs. SCE), thaum tus nqi sib thooj rau cov qauv tsis yog lom yog kwv yees li ntawm -442 mV (vs. aeruginosa ntawm Eocinosa).
Kev ntsuas hluav taws xob ntawm 2707 HDSS cov qauv hauv nruab nrab abiotic thiab Pseudomonas aeruginosa broth ntawm 37 ° C:
(a) Eocp raws li kev ua haujlwm ntawm lub sijhawm raug, (b) polarization nkhaus ntawm hnub 14, (c) Rp ua haujlwm ntawm lub sijhawm raug thiab (d) icorr ua haujlwm ntawm lub sijhawm raug.
Table 3 teev cov electrochemical corrosion parameter qhov tseem ceeb ntawm 2707 HDSS cov qauv raug rau abiotic nruab nrab thiab Pseudomonas aeruginosa inoculated nruab nrab rau 14 hnub.Cov tangents ntawm anodic thiab cathodic curves tau extrapolated mus txog rau ntawm cov kev sib tshuam yielding corrosion tam sim no ntom ntom (β thiab β) corrosion Standard method30,31.
Raws li pom hauv daim duab 2b, qhov kev hloov pauv ntawm P. aeruginosa nkhaus ua rau muaj kev nce hauv Ecorr piv nrog abiotic nkhaus.Tus nqi icorr, uas yog proportional rau tus nqi corrosion, nce mus rau 0.328 μA cm-2 nyob rau hauv cov qauv Pseudomonas aeruginosa, plaub zaug ntawm cov qauv uas tsis yog-tshuaj lom neeg (0. μA cm-2).
LPR yog ib qho classic uas tsis muaj kev puas tsuaj electrochemical rau kev tshawb xyuas corrosion ceev.Nws kuj tau siv los kawm MIC32.Daim duab 2c qhia cov polarization tsis kam (Rp) raws li kev ua haujlwm ntawm lub sijhawm raug.A siab dua Rp tus nqi txhais tau tias tsawg dua corrosion.Hauv thawj 24 teev, Rp ntawm 2707 HDSS mus txog tus nqi siab tshaj plaws ntawm 1952 cm2euΩs thiab cov qauv ntawm 1952 cmΩ onas aeruginosa samples.Daim duab 2c kuj qhia tau hais tias tus nqi Rp poob sai sai tom qab ib hnub thiab tom qab ntawd tseem tsis tau hloov pauv rau 13 hnub tom ntej.Rp tus nqi ntawm cov qauv Pseudomonas aeruginosa yog kwv yees li 40 kΩ cm2, uas yog qis dua li ntawm 450 kΩ cm2 tus nqi ntawm cov qauv tsis yog-.
Tus nqi icorr yog proportional rau tus nqi corrosion tsis zoo.Nws tus nqi tuaj yeem xam los ntawm cov kab zauv hauv qab no Stern-Geary,
Follow Zou et al.33, tus nqi ib txwm ntawm Tafel txoj kab nqes B hauv txoj haujlwm no tau suav tias yog 26 mV / dec.Daim duab 2d qhia tau hais tias tus icorr ntawm cov qauv uas tsis yog-biological 2707 tseem nyob ruaj khov, thaum cov qauv P. aeruginosa hloov pauv tau zoo heev tom qab thawj 24 teev.Qhov kev txiav txim siab ntawm qhov tsis zoo ntawm P. -biological tswj.Qhov kev sib txawv no zoo ib yam nrog cov txiaj ntsig polarization tsis kam.
EIS yog lwm cov txheej txheem nondestructive siv los ua tus yam ntxwv ntawm cov tshuaj electrochemical ntawm corroded interfaces.Impedance spectra thiab xam capacitance qhov tseem ceeb ntawm cov qauv raug rau abiotic media thiab Pseudomonas aeruginosa tov, Rb tsis kam ntawm passive zaj duab xis / biofilm tsim nyob rau saum npoo ntawm cov qauv, Rct tus nqi hluav taws xob hloov mus rau EDL (Cdl capacitance), C lement (CPE) parameters.Cov kev ntsuas no tau txheeb xyuas ntxiv los ntawm kev haum cov ntaub ntawv siv tus qauv sib npaug (EEC).
Daim duab 3 qhia txog Nyquist cov phiaj xwm (a thiab b) thiab Bode plots (a' thiab b') ntawm 2707 HDSS cov qauv hauv abiotic nruab nrab thiab P. aeruginosa broth rau txawv incubation times.Qhov txoj kab uas hla ntawm Nyquist nplhaib txo nyob rau hauv lub xub ntiag ntawm Pseudomonas aeruginosa.The Bode plotbation ntawm tag nrho (Fig). Lub sij hawm so tsis tu ncua tuaj yeem muab los ntawm theem maxima.Daim duab 4 qhia cov monolayer (a) thiab bilayer (b) raws li cov qauv ntawm lub cev thiab lawv qhov sib thooj EECs.CPE yog nkag rau hauv EEC qauv.Qhov kev lees paub thiab impedance tau qhia raws li hauv qab no:
Ob lub cev qauv thiab sib npaug sib npaug circuits rau haum lub impedance spectrum ntawm 2707 HDSS qauv:
qhov twg Y0 yog qhov loj ntawm CPE, j yog tus lej xav txog lossis (-1) 1/2, ω yog angular zaus, thiab n yog CPE zog Performance index tsawg dua unity35.Qhov inverse ntawm tus nqi hloov pauv tsis kam (xws li 1/Rct) sib haum rau tus nqi corrosion.Smallr Rct txhais tau hais tias ceev dua corrosion ntawm 14 hnub ntawm PRT. aeruginosa cov qauv mus txog 32 kΩ cm2, ntau me dua li 489 kΩ cm2 ntawm cov qauv uas tsis yog lom (Table 4).
Cov duab CLSM thiab SEM cov duab hauv daim duab 5 qhia meej meej tias cov ntaub ntawv biofilm nyob rau saum npoo ntawm 2707 HDSS cov qauv tom qab 7 hnub yog ntom.Txawm li cas los xij, tom qab 14 hnub, cov ntaub ntawv biofilm tau sib cais thiab qee lub hlwb tuag tshwm sim.Table 5 qhia txog biofilm thickness ntawm 2707 HDSS qhov siab tshaj plaws rau 1 hnub tom qab examination. thickness hloov los ntawm 23.4 μm tom qab 7 hnub mus rau 18.9 μm tom qab 14 hnub.Qhov nruab nrab biofilm thickness kuj paub tseeb tias qhov kev hloov no.Nws poob ntawm 22.2 ± 0.7 μm tom qab 7 hnub mus rau 17.8 ± 1.0 μm tom qab 14 hnub.
(a) 3-D CLSM duab tom qab 7 hnub, (b) 3-D CLSM duab tom qab 14 hnub, (c) SEM duab tom qab 7 hnub thiab (d) SEM duab tom qab 14 hnub.
EDS nthuav tawm cov khoom siv tshuaj lom neeg hauv biofilms thiab cov khoom siv corrosion ntawm cov qauv raug rau P. aeruginosa rau 14 hnub.Daim duab 6 qhia tau hais tias cov ntsiab lus ntawm C, N, O, thiab P hauv biofilms thiab corrosion khoom yog ntau dua li cov hlau liab qab, vim tias cov ntsiab lus no cuam tshuam nrog biofilms thiab lawv cov metabolites.Microbes tsuas yog xav tau cov kab mob Fe thiab corrosion ntawm H. qhov saum npoo ntawm cov qauv qhia tau hais tias cov hlau matrix tau poob cov ntsiab lus vim corrosion.
Tom qab 14 hnub, pitting nrog thiab tsis muaj P. aeruginosa tau pom nyob rau hauv 2216E nruab nrab.Ua ntej incubation, cov specimen nto yog du thiab tsis muaj qhov tsis xws luag (Daim duab 7a). ntawm cov qauv uas tsis yog-biological tswj (qhov siab tshaj plaws qhov tob 0.02 μm).Qhov siab tshaj qhov qhov tob tshwm sim los ntawm Pseudomonas aeruginosa yog 0.52 μm tom qab 7 hnub thiab 0.69 μm tom qab 14 hnub, raws li qhov nruab nrab qhov siab qhov tob ntawm 3 cov qauv (10 qhov siab tshaj plaws qhov tob rau txhua tus qauv .0 ± 2 m) 52 ± 0.15 μm, ntsig txog (Table 5).Cov qhov tob qhov tob no yog qhov me me tab sis tseem ceeb.
(a) Ua ntej raug, (b) 14 hnub nyob rau hauv nruab nrab abiotic thiab (c) 14 hnub hauv Pseudomonas aeruginosa broth.
Daim duab 8 qhia txog XPS spectra ntawm cov qauv sib txawv, thiab cov tshuaj muaj pes tsawg leeg tshuaj ntsuam xyuas rau txhua qhov saum npoo tau sau tseg hauv Table 6.In Table 6, atomic feem pua ​​​​ntawm Fe thiab Cr nyob rau hauv lub xub ntiag ntawm P. aeruginosa (cov qauv A thiab B) tau qis dua li cov qauv uas tsis yog-biological tswj cov qauv (Rau cov qauv Pspect 2 cores, D). nkhaus yog haum rau plaub lub ncov Cheebtsam nrog binding zog (BE) qhov tseem ceeb ntawm 574.4, 576.6, 578.3 thiab 586.8 eV, uas muaj peev xwm raug ntaus nqi rau Cr, Cr2O3, CrO3 thiab Cr (OH) 3, raws li (Fig. peaks rau Cr (573.80 eV rau BE) thiab Cr2O3 (575.90 eV rau BE) nyob rau hauv daim duab 9c thiab d, ntsig txog.Qhov sib txawv tshaj plaws ntawm cov qauv abiotic thiab P. aeruginosa yog qhov muaj Cr6+ thiab ntau dua cov txheeb ze feem ntawm Cr.BE (OH) ntawm 36 BE (OH)
Qhov dav XPS spectra ntawm qhov chaw ntawm 2707 HDSS cov qauv hauv ob qhov kev tshaj tawm yog 7 hnub thiab 14 hnub, feem.
(a) 7 hnub ntawm kev kis tus kab mob P. aeruginosa, (b) 14 hnub ntawm kev kis tus kab mob P. aeruginosa, (c) 7 hnub nyob rau hauv abiotic nruab nrab thiab (d) 14 hnub nyob rau hauv nruab nrab abiotic.
HDSS nthuav tawm cov qib siab ntawm corrosion kuj nyob rau hauv feem ntau ib puag ncig.Kim li al.2 tau tshaj tawm tias UNS S32707 HDSS tau txhais tias yog DSS alloyed heev nrog PREN ntawm ntau dua 45.Tus nqi PREN ntawm 2707 HDSS cov qauv hauv cov haujlwm no yog 49.Qhov no yog vim nws cov ntsiab lus chromium siab thiab siab molybdenum thiab Ni theem, uas muaj txiaj ntsig zoo nyob rau hauv acidic thiab high chloride deformation ib puag ncig. Cov qauv kev ruaj ntseg thiab corrosion kuj.Txawm li cas los xij, txawm tias nws cov tshuaj tiv thaiv zoo heev, cov ntaub ntawv sim hauv cov haujlwm no qhia tias 2707 HDSS tsis muaj kev tiv thaiv tag nrho rau MIC ntawm P. aeruginosa biofilms.
Electrochemical cov txiaj ntsig tau pom tias tus nqi corrosion ntawm 2707 HDSS hauv P. aeruginosa broth tau nce ntxiv tom qab 14 hnub piv rau qhov nruab nrab tsis muaj roj ntsha.Raws li daim duab 2a, qhov txo qis hauv Eocp tau pom nyob rau hauv ob qho tib si abiotic nruab nrab thiab P. aeruginosa broth thaum thawj 24 teev. , theem ntawm cov roj ntsha Eocp yog ntau dua li cov uas tsis yog-biological Eocp.Yog vim li cas ntseeg hais tias qhov sib txawv no yog vim P. aeruginosa biofilm tsim.Nyob rau hauv daim duab 2d, nyob rau hauv lub xub ntiag ntawm P. aeruginosa, tus nqi icorr ntawm 2707 HDSS mus txog 0.627 μA qhov kev txiav txim siab ntawm a 6 cm-2. 2), uas yog raws li tus nqi Rct ntsuas los ntawm EIS.Nyob rau hauv thawj ob peb hnub, impedance qhov tseem ceeb nyob rau hauv P. aeruginosa broth tau nce vim qhov txuas ntawm P. aeruginosa hlwb thiab tsim ntawm biofilms.Txawm li cas los xij, thaum lub biofilm tag nrho npog qhov chaw ntawm qhov hnoos qeev, impedance txo qis.Qhov kev tiv thaiv ntawm cov txheej txheem biofilm yog thawj zaug, thiab cov txheej txheem tiv thaiv biofilm. corrosion kuj txo lub sij hawm, thiab cov Symptoms ntawm P. aeruginosa ua rau localized corrosion.Qhov sib txawv ntawm abiotic media yog txawv.Qhov corrosion kuj ntawm cov tsis-biological tswj tau ntau dua li tus nqi sib thooj ntawm cov qauv raug rau P. aeruginosa broth. Tsis tas li ntawd, rau cov qauv kuaj abiotic, tus nqi Rct ntawm 2707 42 hnub ntawm 1000 r. 32 kΩ cm2) nyob rau hauv lub xub ntiag ntawm P. aeruginosa.Yog li ntawd, 2707 HDSS muaj zoo heev corrosion kuj nyob rau hauv ib tug sterile ib puag ncig, tab sis tsis resistant rau MIC nres los ntawm P. aeruginosa biofilms.
Cov txiaj ntsig no tseem tuaj yeem pom los ntawm cov polarization nkhaus hauv daim duab 2b.Cov anodic branching tau ntaus nqi los ntawm Pseudomonas aeruginosa biofilm tsim thiab hlau oxidation cov tshuaj tiv thaiv.Tam sim no cov tshuaj tiv thaiv cathodic yog txo cov pa oxygen.Qhov muaj P. aeruginosa zoo heev ua rau lub zog corrosion tam sim no ntawm aeruginosa. m nce hauv zos corrosion ntawm 2707 HDSS.Yuan et al29 pom tias qhov corrosion tam sim no ntom ntawm 70/30 Cu-Ni alloy nce nyob rau hauv kev sib tw ntawm P. aeruginosa biofilm.Qhov no tej zaum yuav yog vim biocatalysis ntawm oxygen txo los ntawm Pseudomonas aeruginosa biofilms.Qhov kev soj ntsuam ntawm no kuj tseem muaj cov biofilm SS20. Hauv qab ntawm lawv.Yog li ntawd, qhov tsis ua haujlwm rov ua dua cov hlau saum npoo los ntawm cov pa oxygen tuaj yeem yog qhov ua rau MIC hauv txoj haujlwm no.
Dickinson thiab al.38 qhia tias tus nqi ntawm cov tshuaj lom neeg thiab cov tshuaj electrochemical tuaj yeem cuam tshuam ncaj qha los ntawm kev ua haujlwm metabolic ntawm cov kab mob sessile ntawm cov qauv thiab qhov xwm ntawm cov khoom siv corrosion.Raws li pom hauv daim duab 5 thiab Table 5, ob qho tib si xov tooj ntawm tes thiab biofilm thickness poob tom qab 14 hnub.Qhov no tuaj yeem tsim nyog piav qhia tias tom qab 14 hnub ntawm cov khoom siv corrosion.Raws li pom hauv daim duab 5. nyob rau hauv 2216E nruab nrab los yog tso tawm cov tshuaj lom hlau ions los ntawm 2707 HDSS matrix.Qhov no yog ib qho kev txwv ntawm batch thwmsim.
Hauv kev ua haujlwm no, P. aeruginosa biofilm txhawb nqa lub zos depletion ntawm Cr thiab Fe hauv qab cov biofilm ntawm 2707 HDSS nto (Fig. 6).Table 6, qhov txo qis ntawm Fe thiab Cr hauv cov qauv D piv rau cov qauv C, qhia tias yaj Fe thiab Cr tshwm sim los ntawm P. aeruginosa sim 7 hnub dhau los ntawm thawj 2 hnub biofilm. Marine ib puag ncig.Nws muaj 17700 ppm Cl-, uas yog piv rau cov uas pom nyob rau hauv tej yam ntuj tso seawater.Qhov muaj 17700 ppm Cl- yog lub ntsiab yog vim li cas rau qhov txo nyob rau hauv Cr nyob rau hauv 7- thiab 14-hnub abiotic cov qauv tshuaj ntsuam xyuas los ntawm XPS.Piv rau P. aeruginosa cov qauv ntawm 2 Cl- aeruginosa muaj zog ntau dua cov qauv ntawm cov Cr-aeruginosa cov qauv ntawm cov Cr-aeruginosa ntau dua. 7 HDSS nyob rau hauv ib puag ncig abiotic.Daim duab 9 qhia pom muaj Cr6+ nyob rau hauv cov yeeb yaj kiab passivation.Nws tuaj yeem koom nrog kev tshem tawm Cr ntawm steel nto los ntawm P. aeruginosa biofilms, raws li tau hais los ntawm Chen thiab Clayton.
Vim yog cov kab mob loj hlob, pH qhov tseem ceeb ntawm nruab nrab ua ntej thiab tom qab cog yog 7.4 thiab 8.2, ntsig txog.Yog li ntawd, hauv qab P. aeruginosa biofilm, organic acid corrosion tsis zoo li yuav ua rau muaj txiaj ntsig zoo rau txoj haujlwm no vim yog pH siab nyob rau hauv bulk nruab nrab.Qhov pH ntawm cov khoom tsis yog biofilm yog 7. Lub sijhawm kuaj 14-hnub.Qhov nce hauv pH hauv qhov nruab nrab inoculation tom qab incubation yog vim lub metabolic kev ua ntawm P. aeruginosa thiab tau pom tias muaj cov nyhuv tib yam ntawm pH thaum tsis muaj cov ntawv xeem.
Raws li pom nyob rau hauv daim duab 7, qhov siab tshaj plaws qhov tob tshwm sim los ntawm P. aeruginosa biofilm yog 0.69 μm, uas yog ntau npaum li cas ntawm cov abiotic nruab nrab (0.02 μm).Qhov no yog raws li cov electrochemical cov ntaub ntawv tau piav saum toj no.Qhov 0.69 μm pit qhov tob yog ntau tshaj kaum npaug me dua li cov ntaub ntawv qhia txog tus nqi 9.5st. 2707 HDSS nthuav tawm MIC zoo dua piv rau 2205 DSS.Qhov no yuav tsum tsis muaj qhov xav tsis thoob, vim 2707 HDSS muaj cov ntsiab lus chromium ntau dua, muab kev ua haujlwm ntev dua, vim tias cov qauv sib npaug tsis muaj teeb meem theem nrab precipitates, ua rau nws nyuaj rau P. aeruginosa depassivate thiab pib cov ntsiab lus eclipse.
Hauv kev xaus, MIC pitting tau pom nyob rau saum npoo ntawm 2707 HDSS hauv P. aeruginosa broth piv rau negligible pitting nyob rau hauv abiotic media.Qhov kev ua haujlwm no qhia tau hais tias 2707 HDSS muaj MIC zoo dua li 2205 DSS, tab sis nws tsis muaj kev tiv thaiv tag nrho rau MIC vim P. aeruginosa biofilm.Cov kev tshawb pom ntawm stainless hlau qhov kev pab cuam lub neej.
Daim coupon rau 2707 HDSS yog muab los ntawm Lub Tsev Kawm Ntawv ntawm Metallurgy ntawm Northeastern University (NEU) nyob rau hauv Shenyang, Tuam Tshoj.Cov ntsiab lus ntawm 2707 HDSS yog qhia nyob rau hauv Table 1, uas tau soj ntsuam los ntawm NEU Materials Analysis thiab Test Department.Tag nrho cov qauv raug kho kho ntawm 1180 ° C rau 1 teev SS corrosion zoo li 1 teev. thaj tsam ntawm 1 cm2 yog polished mus rau 2000 grit nrog silicon carbide ntawv thiab ntxiv polished nrog ib tug 0.05 μm Al2O3 hmoov suspension.Cov sab thiab hauv qab yog tiv thaiv los ntawm inert xim.Tom qab ziab, cov specimens tau rinsed nrog sterile deionized dej thiab sterilized nrog rau 75%. ultraviolet (UV) lub teeb rau 0.5 teev ua ntej siv.
Marine Pseudomonas aeruginosa MCCC 1A00099 strain tau yuav los ntawm Xiamen Marine Culture Collection Center (MCCC), China.Pseudomonas aeruginosa tau loj hlob aerobically ntawm 37 ° C hauv 250 ml flasks thiab 500 ml Vam tias electrochemical iav hlwb siv Marine 2216, China Co., Ltd. um (g/L): 19.45 NaCl, 5.98 MgCl2, 3.24 Na2SO4, 1.8 CaCl2, 0.55 KCl, 0.16 Na2CO3, 0.08 KBr, 0.034 SrCl2, 0.08 SrBr402 HBO 30. 3, 0016 NH3, 0016 NaH2PO4, 5.0 peptone, 1.0 poov xab extract thiab 0.1 ferric citrate.Autoclave ntawm 121 ° C rau 20 feeb ua ntej inoculation. suav sessile thiab planktonic hlwb siv lub hemocytometer nyob rau hauv ib tug 40 ferric citrate cell. tam sim ntawd tom qab inoculation yog kwv yees li 106 hlwb / ml.
Electrochemical xeem tau ua nyob rau hauv ib tug classic peb-electrode iav cell nrog ib tug nruab nrab ntim ntawm 500 ml.Ib daim ntawv platinum thiab ib tug saturated calomel electrode (SCE) tau txuas nrog lub reactor ntawm Luggin capillaries uas muaj ntsev txuas hniav, ua hauj lwm raws li lub txee thiab siv electrodes, raws li tau zoo raws li rau cov ua hauj lwm electrodes, aperoxye coated nrog ib tug 1 cm npog. 2 ntawm qhov chaw ib puag ncig sab nraud rau qhov chaw ua haujlwm electrode.Thaum lub sijhawm ntsuas electrochemical, cov qauv tau muab tso rau hauv 2216E nruab nrab thiab khaws cia ntawm qhov ntsuas kub tsis tu ncua (37 ° C) hauv cov dej da dej.OCP, LPR, EIS thiab cov ntaub ntawv muaj peev xwm dynamic polarization tau ntsuas los ntawm Autolab potentiostat (Reference 600s incbation, US). 0.125 mV s-1 tshaj qhov ntau ntawm -5 thiab 5 mV nrog Eocp thiab ib qho piv txwv zaus ntawm 1 Hz.EIS tau ua nrog sine yoj nyob rau hauv ntau zaus ntawm 0.01 txog 10,000 Hz siv 5 mV thov voltage ntawm lub xeev ruaj khov Eocp.Ua ntej qhov muaj peev xwm ua kom tsis muaj zog. larization curves ces khiav ntawm -0.2 mus rau 1.5 V vs. Eocp ntawm tus nqi scan ntawm 0.166 mV/s.Txhua qhov kev sim tau rov ua dua 3 zaug nrog thiab tsis muaj P. aeruginosa.
Cov khoom siv rau kev tshuaj ntsuam metallographic tau mechanically polished nrog 2000 grit ntub SiC daim ntawv thiab tom qab ntawd ntxiv polished nrog 0.05 μm Al2O3 hmoov raug tshem tawm rau kev soj ntsuam qhov muag.Metallographic tsom tau siv lub tshuab ntsuas qhov muag.Cov qauv tau etched nrog 10 wt.% potassium hydroxide tov 43.
Tom qab incubation, cov qauv raug ntxuav 3 zaug nrog phosphate-buffered saline (PBS) tov (pH 7.4 ± 0.2) thiab tom qab ntawd kho nrog 2.5% (v/v) glutaraldehyde rau 10 teev los kho biofilms.Nws yog tom qab lub cev qhuav dej nrog ib tug graded series 6% 0.5%, 0.5%, 0.0%, 0% v/v) ntawm ethanol ua ntej huab cua kom qhuav. Thaum kawg, qhov saum npoo ntawm cov qauv yog sputtered nrog ib tug kub zaj duab xis los muab conductivity rau SEM kev soj ntsuam.Cov SEM dluab tau tsom rau cov me ntsis nrog cov feem ntau sessile P. aeruginosa hlwb nyob rau saum npoo ntawm txhua tus qauv.Perform EDS tsom xam kom pom cov tshuaj lom neeg SEM .A Zeiss Confocal (SEM CL7), Lub teb chaws Yelemees siv cov khoom siv Zeiss (Scan) ntsuas lub qhov tob.In thiaj li yuav soj ntsuam cov corrosion pits nyob rau hauv lub biofilm, lub xeem daim yog thawj zaug ntxuav raws li lub teb chaws Suav Standard (CNS) GB / T4334.4-2000 kom tshem tawm cov khoom corrosion thiab biofilm nyob rau saum npoo ntawm daim ntawv xeem.
X-ray photoelectron spectroscopy (XPS, ESCALAB250 nto tsom xam qhov system, Thermo VG, USA) kev tsom xam tau ua los ntawm kev siv lub monochromatic X-ray qhov chaw (txhuas Kα kab ntawm 1500 eV zog thiab 150 W fais fab tuag) dhau qhov kev sib txuas ntawm lub zog ntau yam 0 raws li cov txheej txheem cov ntaub ntawv -1350 5-0 eV eV. 2 eV step size.
Cov incubated specimens raug tshem tawm thiab yaug maj mam nrog PBS (pH 7.4 ± 0.2) rau 15 s45.To soj ntsuam cov kab mob viability ntawm biofilms ntawm cov qauv, cov biofilms tau stained siv LIVE/DEAD BacLight Bacterial Viability Kit (Invitrogen, Eugene), ob lub khoom siv fluorescent, USA. Nyob rau hauv CLSM, dots nrog fluorescent ntsuab thiab liab sawv cev rau cov nyob thiab tuag hlwb, feem.Rau staining, ib tug 1 ml sib tov uas muaj 3 μl SYTO-9 thiab 3 μl PI tov yog incubated rau 20 feeb nyob rau hauv chav tsev kub (23). wavelengths (488 nm rau cov hlwb nyob thiab 559 nm rau cov hlwb tuag) siv lub tshuab Nikon CLSM (C2 Plus, Nikon, Nyiv). Biofilm thickness tau ntsuas hauv 3-D scanning hom.
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