Cov nyhuv ntawm Pseudomonas aeruginosa Marine Biofilm ntawm Microbial Corrosion ntawm 2707 Super Duplex Stainless Hlau

Ua tsaug rau koj tuaj xyuas Nature.com.Koj siv lub browser version nrog kev txhawb nqa CSS tsawg.Rau qhov kev paub zoo tshaj plaws, peb xav kom koj siv qhov browser tshiab (lossis lov tes taw Compatibility Hom hauv Internet Explorer).Tsis tas li ntawd, txhawm rau xyuas kom muaj kev txhawb nqa tsis tu ncua, peb qhia lub vev xaib tsis muaj qauv thiab JavaScript.
Qhia ib lub carousel ntawm peb slides ib zaug.Siv cov nyees khawm dhau los thiab Tom ntej kom txav mus los ntawm peb qhov swb ib zaug, lossis siv cov khawm slider thaum kawg kom txav mus los ntawm peb qhov swb ib zaug.
Microbial corrosion (MIC) yog ib qho teeb meem loj hauv ntau qhov kev lag luam vim nws tuaj yeem ua rau poob nyiaj txiag loj.Super duplex stainless hlau 2707 (2707 HDSS) yog siv nyob rau hauv marine ib puag ncig vim nws cov tshuaj tiv thaiv zoo heev.Txawm li cas los xij, nws qhov kev tawm tsam rau MIC tsis tau sim ua kom pom.Txoj kev tshawb no tau tshuaj xyuas tus cwj pwm ntawm MIC 2707 HDSS tshwm sim los ntawm cov kab mob marine aerobic Pseudomonas aeruginosa.Electrochemical tsom xam pom tau hais tias nyob rau hauv lub xub ntiag ntawm Pseudomonas aeruginosa biofilm nyob rau hauv nruab nrab 2216E, lub corrosion kuj hloov tau zoo, thiab corrosion tam sim no ceev.Cov txiaj ntsig ntawm X-ray photoelectron spectroscopy (XPS) tsom xam pom qhov txo qis hauv Cr cov ntsiab lus ntawm cov qauv saum npoo hauv qab biofilm.Kev soj ntsuam ntawm cov duab hauv qhov pom tau tias Pseudomonas aeruginosa biofilms tsim qhov siab tshaj plaws qhov tob ntawm 0.69 µm tom qab 14 hnub ntawm kab lis kev cai.Txawm hais tias qhov no me me, nws qhia tias 2707 HDSS tsis muaj kev tiv thaiv tag nrho rau cov teebmeem ntawm P. aeruginosa biofilms ntawm MIC.
Duplex stainless hlau (DSS) yog dav siv nyob rau hauv ntau yam kev lag luam vim yog kev sib xyaw ua ke zoo tshaj plaws ntawm cov khoom siv kho tshuab thiab corrosion kuj 1,2.Txawm li cas los xij, hauv zos pitting tseem tuaj yeem tshwm sim, uas tuaj yeem cuam tshuam rau kev ncaj ncees ntawm cov hlau no 3, 4 .DSS tsis tiv thaiv microbial corrosion (MIC) 5,6.Txawm hais tias daim ntawv thov ntau yam ntawm DSS yog dav heev, tseem muaj ib puag ncig uas qhov corrosion kuj ntawm DSS tsis txaus rau kev siv mus ntev.Qhov no txhais tau tias cov ntaub ntawv kim dua uas yuav tsum tau muaj kev tiv thaiv corrosion ntau dua.Jeon et al.7 pom tias txawm tias super duplex stainless hlau (SDSS) muaj qee qhov kev txwv ntawm kev tiv thaiv corrosion.Yog li ntawd, yuav tsum muaj super duplex stainless hlau (HDSS) nrog corrosion kuj ntau dua nyob rau hauv tej yam kev siv.Qhov no coj mus rau txoj kev loj hlob ntawm high alloyed HDSS.
Qhov kev tiv thaiv corrosion ntawm DSS yog txiav txim los ntawm qhov piv ntawm α-theem rau γ-theem thiab cov cheeb tsam depleted hauv Cr, Mo thiab W nyob ib sab mus rau theem nrab theem 8,9,10.HDSS muaj cov ntsiab lus siab ntawm Cr, Mo thiab N11, uas muab nws zoo heev corrosion kuj thiab tus nqi siab (45-50) sib npaug pitting tsis kam tus nqi (PREN), uas txhais los ntawm wt.% Cr + 3.3 (wt.% Mo. + 0, 5 wt % W) + 16 wt %.N12.Nws zoo heev corrosion kuj nyob ntawm seb muaj pes tsawg leeg uas muaj kwv yees li 50% ferritic (α) thiab 50% austenitic (γ) theem.HDSS tau txhim kho cov khoom siv kho tshuab thiab cov tshuaj chlorine ntau dua piv rau cov qauv DSS13.Cov yam ntxwv ntawm cov tshuaj corrosion.Kev txhim kho corrosion kuj txuas ntxiv kev siv HDSS nyob rau hauv ntau chloride ib puag ncig xws li marine ib puag ncig.
MIC yog ib qho teeb meem tseem ceeb hauv ntau qhov kev lag luam, suav nrog roj thiab roj thiab dej 14.MIC tso nyiaj rau 20% ntawm tag nrho cov kev puas tsuaj corrosion15.MIC yog bioelectrochemical corrosion uas tuaj yeem pom hauv ntau qhov chaw16.Kev tsim ntawm biofilms ntawm cov hlau qhov chaw hloov cov txheej txheem electrochemical thiab yog li cuam tshuam cov txheej txheem corrosion.Nws feem ntau lees txais tias MIC corrosion yog tshwm sim los ntawm biofilms14.Electrogenic microorganisms noj tawm cov hlau kom tau txais lub zog rau kev ciaj sia17.Cov kev tshawb fawb MIC tsis ntev los no tau qhia tias EET (extracellular electron hloov) yog qhov txwv rau MIC vim yog cov kab mob electrogenic.Zhang et al.18 tau qhia tias cov neeg kho tshuab hluav taws xob nrawm nrawm hloov hluav taws xob ntawm Desulfovibrio vulgaris sessile hlwb thiab 304 stainless hlau, ua rau MIC nres ntau dua.Anning et al.19 and Wenzlaff et al.20 tau pom tias biofilms ntawm corrosive sulfate-txo cov kab mob (SRBs) tuaj yeem nqus cov hluav taws xob ncaj qha los ntawm cov hlau substrates, ua rau muaj qhov hnyav heev.
DSS paub tias yuav raug rau MIC hauv xov xwm uas muaj SRBs, cov kab mob uas txo cov hlau (IRBs), thiab lwm yam. 21 .Cov kab mob no ua rau thaj chaw pitting ntawm qhov chaw ntawm DSS nyob rau hauv biofilm22,23.Tsis zoo li DSS, me ntsis paub txog MIC HDSS24.
Pseudomonas aeruginosa yog kab mob Gram-negative, motile, qws-zoo li tus kab mob uas yog dav faib nyob rau hauv xwm25.Pseudomonas aeruginosa kuj yog lub ntsiab microbiota lub luag haujlwm rau MIC ntawm cov hlau nyob rau hauv marine ib puag ncig26.Pseudomonas hom yog koom ncaj qha rau hauv cov txheej txheem corrosion thiab raug lees paub tias yog thawj colonizers thaum lub sij hawm tsim biofilm27.Mahat et al.28 and Yuan et al.29 pom tau hais tias Pseudomonas aeruginosa nyhav nce qhov corrosion ntawm me me hlau thiab alloys nyob rau hauv dej ib puag ncig.
Lub hom phiaj tseem ceeb ntawm txoj haujlwm no yog los kawm 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 tshuaj xyuas saum npoo thiab tshuaj xyuas cov khoom siv corrosion.Electrochemical kev tshawb fawb suav nrog qhib Circuit Court muaj peev xwm (OCP), linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS) thiab dynamic polarization tau ua los kawm txog tus cwj pwm ntawm MIC 2707 HDSS.Lub zog dispersive spectroscopy (EDS) tsom xam yog ua los xyuas cov tshuaj lom neeg ntawm qhov chaw corroded.Tsis tas li ntawd, kev ruaj ntseg ntawm oxide zaj duab xis passivation nyob rau hauv kev cuam tshuam ntawm ib puag ncig marine uas muaj Pseudomonas aeruginosa tau txiav txim siab los ntawm X-ray photoelectron spectroscopy (XPS).Qhov tob ntawm lub pits tau ntsuas nyob rau hauv lub confocal laser scanning microscope (CLSM).
Table 1 qhia cov tshuaj muaj pes tsawg leeg ntawm 2707 HDSS.Table 2 qhia tau hais tias 2707 HDSS muaj cov khoom siv zoo heev nrog lub zog tawm ntawm 650 MPa.Ntawm daim duab.1 qhia qhov kho qhov muag microstructure ntawm kev daws cov cua sov kho 2707 HDSS.Elongated bands ntawm austenitic thiab ferritic theem yam tsis muaj theem ob tuaj yeem pom hauv microstructure uas muaj kwv yees li 50% austenitic thiab 50% ferritic theem.
Ntawm daim duab.2a qhia qhov qhib Circuit Court muaj peev xwm (Eocp) piv rau lub sijhawm raug rau 2707 HDSS hauv 2216E abiotic nruab nrab thiab Pseudomonas aeruginosa broth rau 14 hnub ntawm 37 ° C.Nws tau pom tias qhov kev hloov pauv tshaj plaws hauv Eocp tau tshwm sim hauv thawj 24 teev.Eocp qhov tseem ceeb hauv ob qhov xwm txheej tau nce siab txog -145 mV (hloov SCE) ntawm li 16 teev thiab tom qab ntawd poob qis mus rau -477 mV (v piv rau SCE) thiab -236 mV (v piv rau SCE) rau cov qauv tsis yog lom thiab P rau cov txheeb ze SCE) patina nplooj, feem.Tom qab 24 teev, Eocp tus nqi ntawm Pseudomonas aeruginosa 2707 HDSS tseem nyob ruaj khov ntawm -228 mV (piv rau SCE), thaum tus nqi sib thooj rau cov qauv uas tsis yog tshuaj lom neeg yog kwv yees li -442 mV (piv rau SCE).Eocp nyob rau hauv lub xub ntiag ntawm Pseudomonas aeruginosa yog tsawg heev.
Electrochemical kuaj ntawm 2707 HDSS kuaj hauv abiotic media thiab Pseudomonas aeruginosa broth ntawm 37 ° C:
(a) Hloov nyob rau hauv Eocp nrog lub sij hawm raug, (b) polarization nkhaus ntawm hnub 14, (c) hloov nyob rau hauv Rp nrog lub sij hawm raug, (d) hloov nyob rau hauv corr nrog lub sij hawm raug.
Table 3 qhia txog cov electrochemical corrosion tsis tau ntawm 2707 HDSS cov qauv raug rau abiotic thiab P. aeruginosa inoculated media nyob rau lub sij hawm ntawm 14 hnub.Tangential extrapolation ntawm anodic thiab cathodic nkhaus mus rau qhov sib tshuam taw tes tso cai rau kev txiav txim siab ntawm corrosion tam sim no ceev (icorr), corrosion muaj peev xwm (Ecorr) thiab Tafel txoj kab nqes (βα thiab βc) raws li tus qauv txheej txheem30,31.
Raws li pom hauv daim duab 2b, qhov kev hloov pauv ntawm P. aeruginosa nkhaus ua rau muaj qhov nce hauv Ecorr piv rau abiotic nkhaus.Tus nqi icorr ntawm cov qauv uas muaj Pseudomonas aeruginosa, proportional rau tus nqi corrosion, nce mus rau 0.328 µA cm-2, uas yog plaub npaug ntau dua li ntawm cov qauv uas tsis yog bio (0.087 µA cm-2).
LPR yog cov txheej txheem electrochemical classic rau kev tshawb xyuas tsis muaj kev puas tsuaj ntawm corrosion.Nws kuj tau siv los kawm MIC32.Ntawm daim duab.2c qhia txog kev hloov pauv ntawm qhov polarization tsis kam (Rp) nyob ntawm lub sijhawm raug.Tus nqi Rp ntau dua txhais tau tias tsawg dua corrosion.Hauv thawj 24 teev, Rp 2707 HDSS peaked ntawm 1955 kΩ cm2 rau cov qauv uas tsis yog lom thiab 1429 kΩ cm2 rau Pseudomonas aeruginosa specimens.Daim duab 2c kuj qhia tau hais tias tus nqi Rp tau txo qis sai tom qab ib hnub thiab tom qab ntawd tseem tsis tau hloov pauv li ntawm 13 hnub tom ntej.Tus nqi Rp rau Pseudomonas aeruginosa test specimen yog kwv yees li 40 kΩ cm2, uas yog qis dua li 450 kΩ cm2 tus nqi rau cov qauv kuaj tsis yog lom.
Tus nqi ntawm icorr yog proportional rau lub uniform corrosion tus nqi.Nws tus nqi tuaj yeem xam los ntawm cov kab zauv hauv qab no Stern-Giri:
Raws li Zoe et al.33 Tafel txoj kab nqes B tau raug coj los ua tus nqi ntawm 26 mV / dec hauv qhov haujlwm no.Ntawm daim duab.2d qhia tau hais tias qhov icorr ntawm 2707 abiotic hom tseem nyob ruaj khov, thaum lub icorr ntawm Pseudomonas aeruginosa band hloov pauv tau zoo nrog dhia loj tom qab thawj 24 teev.Tus nqi icorr ntawm Pseudomonas aeruginosa kuaj qauv yog ib qho kev txiav txim ntawm qhov loj dua qhov kev tswj tsis yog lom.Cov qauv no zoo ib yam nrog cov txiaj ntsig ntawm polarization tsis kam.
EIS yog lwm txoj hauv kev uas tsis yog kev puas tsuaj uas siv los ua tus yam ntxwv ntawm cov tshuaj tiv thaiv electrochemical ntawm corrosion interface34.Impedance spectra thiab capacitance xam cov strips raug rau abiotic media thiab cov kev daws teeb meem ntawm Pseudomonas aeruginosa, Rb yog qhov tsis kam ntawm passive / biofilm tsim rau ntawm qhov chaw ntawm lub sawb, Rct yog tus nqi hloov pauv tsis kam, Cdl yog hluav taws xob ob txheej.) thiab QCPE yam tsis tu ncua theem (CPE) tsis.Cov kev ntsuas no tau txheeb xyuas ntxiv los ntawm kev sib piv cov ntaub ntawv nrog rau cov qauv hluav taws xob sib npaug (EEC).
Ntawm daim duab.3 qhia txog Nyquist plots (a thiab b) thiab Bode plots (a' thiab b') ntawm 2707 HDSS kuaj hauv abiotic media thiab Pseudomonas aeruginosa broth ntawm ntau lub sijhawm incubation.Nyob rau hauv lub xub ntiag ntawm Pseudomonas aeruginosa, txoj kab uas hla ntawm Nyquist voj txo.Cov phiaj xwm Bode (Fig. 3b') qhia qhov nce ntawm tag nrho impedance.Cov ntaub ntawv hais txog lub sijhawm so tas li tuaj yeem tau txais los ntawm theem maxima.Ntawm daim duab.4 qhia txog cov qauv ntawm lub cev thiab qhov sib thooj EEC raws li ib txheej (a) thiab ob txheej (b).CPE tau nkag mus rau hauv EEC qauv.Nws 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 2707 HDSS daim coupon impedance spectrum:
Qhov twg Y0 yog qhov loj ntawm CPE, j yog tus lej xav lossis (−1) 1/2, ω yog qhov ntau zaus, thiab n yog CPE lub zog tsawg dua ib qho 35.Tus nqi hloov pauv tsis kam inversion (piv txwv li 1 / Rct) sib raug rau tus nqi corrosion.Tus nqi qis Rct txhais tau hais tias tus nqi corrosion ntau dua 27.Tom qab 14 hnub ntawm incubation, Rct ntawm cov qauv kuaj ntawm Pseudomonas aeruginosa mus txog 32 kΩ cm2, uas yog ntau tsawg tshaj li 489 kΩ cm2 ntawm cov qauv tsis-biological test (Table 4).
CLSM cov duab thiab SEM cov duab hauv daim duab.5 qhia meej meej tias cov ntaub ntawv biofilm nyob rau saum npoo ntawm HDSS qauv 2707 yog tuab heev tom qab 7 hnub.Txawm li cas los xij, tom qab 14 hnub cov txheej txheej biofilm tau tawg thiab qee lub hlwb tuag tshwm.Table 5 qhia txog biofilm tuab ntawm 2707 HDSS kuaj tom qab 7 thiab 14 hnub ntawm kev raug rau Pseudomonas aeruginosa.Qhov siab tshaj plaws biofilm thickness hloov ntawm 23.4 µm tom qab 7 hnub rau 18.9 µm tom qab 14 hnub.Qhov nruab nrab biofilm tuab kuj tau lees paub qhov qauv no.Nws poob ntawm 22.2 ± 0.7 μm tom qab 7 hnub rau 17.8 ± 1.0 μm tom qab 14 hnub.
(a) 3-D CLSM duab ntawm 7 hnub, (b) 3-D CLSM duab ntawm 14 hnub, (c) SEM duab ntawm 7 hnub, thiab (d) SEM duab ntawm 14 hnub.
EMF nthuav tawm cov khoom siv tshuaj lom neeg hauv biofilm thiab cov khoom siv corrosion ntawm cov qauv raug rau Pseudomonas aeruginosa rau 14 hnub.Ntawm daim duab.Daim duab 6 qhia tau hais tias cov ntsiab lus ntawm C, N, O, P nyob rau hauv biofilm thiab corrosion khoom yog ntau dua nyob rau hauv cov hlau ntshiab, vim hais tias cov ntsiab lus no txuam nrog cov biofilm thiab nws cov metabolites.Cov kab mob tsuas yog xav tau cov lej ntawm Cr thiab Fe.Cov ntsiab lus siab ntawm Cr thiab Fe nyob rau hauv biofilm thiab corrosion khoom nyob rau saum npoo ntawm cov qauv qhia qhov poob ntawm cov ntsiab lus nyob rau hauv cov hlau matrix vim yog corrosion.
Tom qab 14 hnub, pits nrog thiab tsis muaj P. aeruginosa tau pom nyob rau hauv nruab nrab 2216E.Ua ntej incubation, qhov saum npoo ntawm cov qauv yog du thiab tsis muaj qhov tsis xws luag (Daim duab 7a).Tom qab incubation thiab tshem tawm cov khoom siv biofilm thiab corrosion, qhov tob tshaj plaws ntawm cov qauv raug kuaj xyuas siv CLSM, raws li qhia hauv daim duab 7b thiab c.Tsis muaj qhov pom tseeb pitting tau pom nyob rau saum npoo ntawm kev tswj tsis yog lom (qhov siab tshaj qhov tob 0.02 µm).Qhov siab tshaj plaws 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 tau xaiv rau txhua tus qauv) thiab mus txog 0. 42 ± 0.12 µm .thiab 0.52 ± 0.15 µm, ntsig txog (Table 5).Cov dimple qhov tob qhov tseem ceeb no me me tab sis tseem ceeb.
(a) ua ntej raug;(b) 14 hnub nyob rau hauv ib puag ncig abiotic;(c) 14 hnub hauv P. aeruginosa broth.
Ntawm daim duab.Table 8 qhia txog XPS spectra ntawm ntau yam qauv saum npoo, thiab chemistry soj ntsuam rau txhua qhov saum npoo tau sau tseg hauv Table 6. Hauv Table 6, atomic feem pua ​​​​ntawm Fe thiab Cr tau qis dua thaum muaj P. aeruginosa (cov qauv A thiab B. ) tshaj nyob rau hauv cov tsis-biological tswj strips.(cov qauv C thiab D).Rau ib qho piv txwv ntawm Pseudomonas aeruginosa, Cr 2p core theem spectral nkhaus tau haum rau plaub qhov siab tshaj plaws nrog kev sib khi zog (BE) ntawm 574.4, 576.6, 578.3 thiab 586.8 eV, uas tau muab rau Cr, Cr2O3, Cr (OH) thiab Cr (O3) 3, raws li daim duab 9a thiab b).Rau cov qauv nonbiological, qhov spectra ntawm cov tub ntxhais theem Cr 2p hauv Fig.9c thiab d muaj ob lub ntsiab ncov ntawm Cr (BE 573.80 eV) thiab Cr2O3 (BE 575.90 eV), feem.Qhov sib txawv tshaj plaws ntawm daim coupon abiotic thiab P. aeruginosa daim coupon yog qhov muaj Cr6+ thiab feem ntau ntawm Cr(OH)3 (BE 586.8 eV) nyob rau hauv biofilm.
Dav dav XPS spectra ntawm 2707 HDSS cov qauv hauv ob qhov kev tshaj tawm rau 7 thiab 14 hnub, feem.
(a) 7 hnub P. aeruginosa exposure, (b) 14 hnub P. aeruginosa exposure, (c) 7 hnub abiotic exposure, (d) 14 hnub abiotic exposure.
HDSS nthuav tawm qib siab ntawm corrosion kuj nyob rau hauv feem ntau ib puag ncig.Kim et al.2 tau tshaj tawm tias HDSS UNS S32707 tau txheeb xyuas tias yog DSS ntau heev nrog PREN ntau dua 45. Tus nqi PREN ntawm HDSS qauv 2707 hauv txoj haujlwm no yog 49. Qhov no yog vim muaj cov ntsiab lus Cr siab thiab qib siab ntawm Mo thiab Ni, uas muaj txiaj ntsig zoo hauv thaj chaw acidic thiab ib puag ncig nrog cov ntsiab lus siab ntawm chlorides.Tsis tas li ntawd, cov khoom sib npaug zoo thiab tsis muaj qhov tsis zoo microstructure muab cov qauv kev ruaj ntseg thiab corrosion kuj.Txawm hais tias muaj tshuaj tiv thaiv zoo heev, cov ntaub ntawv sim hauv qhov haujlwm no qhia tau tias 2707 HDSS tsis muaj kev tiv thaiv tag nrho rau Pseudomonas aeruginosa biofilm MICs.
Electrochemical cov txiaj ntsig tau pom tias tus nqi corrosion ntawm 2707 HDSS hauv Pseudomonas aeruginosa broth tau nce ntau tom qab 14 hnub piv rau qhov chaw tsis muaj roj ntsha.Hauv daim duab 2a, qhov txo qis hauv Eocp tau pom ob qho tib si hauv nruab nrab abiotic thiab hauv P. aeruginosa broth thaum thawj 24 teev.Tom qab ntawd, cov biofilm tiav npog qhov chaw ntawm cov qauv thiab Eocp yuav ruaj khov.Txawm li cas los xij, qib biotic Eocp ntau dua li qib abiotic Eocp.Muaj cov laj thawj ntseeg tias qhov sib txawv no cuam tshuam nrog kev tsim ntawm P. aeruginosa biofilms.Ntawm daim duab.2g, tus nqi icorr ntawm 2707 HDSS mus txog 0.627 µA cm-2 nyob rau hauv lub xub ntiag ntawm Pseudomonas aeruginosa, uas yog ib qho kev txiav txim ntawm magnitude siab tshaj qhov uas tsis yog-biological tswj (0.063 µA cm-2), uas yog raws li cov Rct. tus nqi ntsuas los ntawm EIS.Thaum thawj ob peb hnub, qhov impedance qhov tseem ceeb hauv P. aeruginosa broth tau nce vim qhov txuas ntawm P. aeruginosa hlwb thiab tsim biofilm.Txawm li cas los xij, qhov impedance txo qis thaum biofilm tag nrho npog cov qauv saum npoo.Cov txheej tiv thaiv yog tawm tsam feem ntau vim yog tsim ntawm biofilm thiab biofilm metabolites.Yog li ntawd, corrosion kuj txo lub sij hawm, thiab deposits ntawm Pseudomonas aeruginosa ua rau lub zos corrosion.Cov kev xav hauv ib puag ncig abiotic txawv.Qhov kev tiv thaiv corrosion ntawm cov kev tswj tsis-biological tau ntau dua li tus nqi sib thooj ntawm cov qauv raug rau Pseudomonas aeruginosa broth.Tsis tas li ntawd, rau cov qauv tshuaj abiotic, tus nqi Rct 2707 HDSS tau mus txog 489 kΩ cm2 hnub 14, uas yog 15 npaug siab dua nyob rau hauv muaj Pseudomonas aeruginosa (32 kΩ cm2).Yog li, 2707 HDSS muaj kev tiv thaiv zoo heev hauv qhov chaw tsis muaj menyuam, tab sis tsis muaj kev tiv thaiv los ntawm MIC nres los ntawm Pseudomonas aeruginosa biofilm.
Cov txiaj ntsig no tseem tuaj yeem pom los ntawm cov kab nkhaus polarization hauv Fig.2b ib.Anodic branching yog txuam nrog Pseudomonas aeruginosa biofilm tsim thiab hlau oxidation cov tshuaj tiv thaiv.Nyob rau tib lub sijhawm, cov tshuaj tiv thaiv cathodic yog txo cov pa oxygen.Lub xub ntiag ntawm P. aeruginosa ua rau muaj kev txhim kho corrosion tam sim no ntom ntom, uas yog hais txog qhov kev txiav txim siab ntau dua li kev tswj hwm abiotic.Qhov no qhia tau hais tias Pseudomonas aeruginosa biofilm txhim kho qhov chaw corrosion ntawm 2707 HDSS.Yuan et al.29 pom tias qhov corrosion tam sim no ntom ntawm 70/30 Cu-Ni alloy tau nce los ntawm Pseudomonas aeruginosa biofilm.Qhov no tej zaum yuav yog vim biocatalysis ntawm oxygen txo los ntawm Pseudomonas aeruginosa biofilm.Qhov kev soj ntsuam no kuj tseem tuaj yeem piav qhia MIC 2707 HDSS hauv txoj haujlwm no.Aerobic biofilms tuaj yeem txo cov pa oxygen hauv qab lawv.Yog li, qhov tsis kam rov ua dua cov hlau nto nrog 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 ncaj qha nyob ntawm kev ua haujlwm ntawm cov kab mob metabolic uas txuas nrog rau cov qauv saum npoo thiab ntawm cov khoom siv corrosion.Raws li pom nyob rau hauv daim duab 5 thiab Table 5, cov cell thiab biofilm thickness txo qis tom qab 14 hnub.Qhov no tuaj yeem piav qhia qhov tseeb los ntawm qhov tseeb tias tom qab 14 hnub feem ntau ntawm cov hlwb anched ntawm 2707 HDSS nto tuag vim kev noj zaub mov tsis zoo hauv 2216E nruab nrab lossis tso tawm cov tshuaj lom hlau ions los ntawm 2707 HDSS matrix.Qhov no yog ib qho kev txwv ntawm kev sim batch.
Hauv kev ua haujlwm no, Pseudomonas aeruginosa biofilm txhawb nqa lub zos depletion ntawm Cr thiab Fe nyob rau hauv biofilm nyob rau saum npoo ntawm 2707 HDSS (Fig. 6).Hauv Table 6, Fe thiab Cr poob qis hauv cov qauv D piv rau cov qauv C, qhia tias Fe thiab Cr dissolution tshwm sim los ntawm P. aeruginosa biofilm tau khaws cia tom qab thawj 7 hnub.2216E ib puag ncig yog siv los simulate ib puag ncig marine.Nws muaj 17700 ppm Cl-, uas yog piv rau nws cov ntsiab lus hauv dej hiav txwv ntuj.Lub xub ntiag ntawm 17700 ppm Cl- yog qhov laj thawj tseem ceeb rau kev txo qis hauv Cr hauv 7-hnub thiab 14-hnub cov qauv uas tsis yog tshuaj lom neeg soj ntsuam los ntawm XPS.Piv nrog rau cov qauv kuaj ntawm Pseudomonas aeruginosa, kev sib cais ntawm Cr hauv cov qauv kuaj abiotic yog tsawg dua vim qhov muaj zog tiv thaiv ntawm 2707 HDSS rau chlorine hauv thaj chaw abiotic.Ntawm daim duab.9 qhia pom muaj Cr6+ hauv zaj duab xis passivating.Qhov no tej zaum yuav muaj feem xyuam rau kev tshem tawm Cr los ntawm steel nto los ntawm P. aeruginosa biofilms, raws li tau hais los ntawm Chen thiab Clayton39.
Vim yog cov kab mob loj hlob, pH qhov nruab nrab ntawm qhov nruab nrab ua ntej thiab tom qab incubation yog 7.4 thiab 8.2, feem.Yog li, corrosion ntawm cov organic acids tsis zoo li yuav pab txhawb rau txoj haujlwm no raws li P. aeruginosa biofilms vim muaj pH siab nyob rau hauv nruab nrab.Cov pH ntawm qhov nruab nrab tsis-biological tswj tsis tau hloov pauv loj heev (los ntawm thawj 7.4 mus rau qhov kawg 7.5) thaum lub sijhawm kuaj 14 hnub.Qhov nce ntawm pH nyob rau hauv nruab nrab inoculum tom qab incubation yog txuam nrog cov metabolic kev ua si ntawm Pseudomonas aeruginosa, thiab tib cov nyhuv ntawm pH tau pom nyob rau hauv tsis muaj lub xeem strip.
Raws li qhia hauv daim duab.7, qhov siab tshaj plaws qhov tob tshwm sim los ntawm Pseudomonas aeruginosa biofilm yog 0.69 µm, uas yog qhov loj dua hauv qhov nruab nrab abiotic (0.02 µm).Qhov no pom zoo nrog cov ntaub ntawv electrochemical saum toj no.Raws li cov xwm txheej zoo ib yam, lub qhov tob ntawm 0.69 µm yog ntau tshaj kaum npaug me dua li 9.5 µm tus nqi teev rau 2205 DSS40.Cov ntaub ntawv no qhia tau hais tias 2707 HDSS nthuav tawm zoo dua rau MICs dua 2205 DSS.Qhov no tsis yog qhov xav tsis thoob vim tias 2707 HDSS muaj qib Cr siab dua, uas tso cai rau kev ua kom ntev dua, ua rau Pseudomonas aeruginosa nyuaj rau depassivate, thiab pib cov txheej txheem yam tsis muaj teeb meem rau yav tom ntej nag lossis daus Pitting41.
Hauv kev xaus, MIC pitting tau pom ntawm 2707 HDSS qhov chaw hauv Pseudomonas aeruginosa broth, thaum pitting yog negligible nyob rau hauv abiotic media.Qhov kev ua haujlwm no qhia tau hais tias 2707 HDSS muaj kev tiv thaiv zoo dua rau MIC dua li 2205 DSS, tab sis nws tsis muaj zog tiv thaiv MIC vim Pseudomonas aeruginosa biofilm.Cov txiaj ntsig no pab xaiv cov hlau tsis zoo thiab lub neej expectancy rau marine ib puag ncig.
Cov qauv 2707 HDSS tau muab los ntawm Lub Tsev Kawm Ntawv ntawm Metallurgy, Northeastern University (NEU), Shenyang, Suav.Lub hauv paus muaj pes tsawg leeg ntawm 2707 HDSS yog qhia hauv Table 1, uas tau soj ntsuam los ntawm Cov Khoom Siv Tshuaj Ntsuam Xyuas thiab Kev Ntsuas ntawm Northeastern University.Tag nrho cov qauv raug kho rau cov kua dej ntawm 1180 ° C rau 1 teev.Ua ntej kev kuaj corrosion, 2707 HDSS npib hlau nrog thaj tsam ntawm thaj tsam ntawm 1 cm2 tau polished rau 2000 grit nrog silicon carbide sandpaper thiab tom qab ntawd ntxiv polished nrog 0.05 µm Al2O3 hmoov slurry.Sab thiab hauv qab yog tiv thaiv nrog inert xim.Tom qab ziab, cov qauv raug ntxuav nrog dej tsis muaj deionized thiab sterilized nrog 75% (v / v) ethanol rau 0.5 h.Tom qab ntawd lawv tau muab cua qhuav nyob rau hauv ultraviolet (UV) lub teeb rau 0.5 teev ua ntej siv.
Marine strain Pseudomonas aeruginosa MCCC 1A00099 tau yuav los ntawm Xiamen Marine Culture Collection (MCCC), Suav teb.Marine 2216E kua nruab nrab (Qingdao Hope Biotechnology Co., Ltd., Qingdao, Suav teb) tau siv los ua kab lis kev cai Pseudomonas aeruginosa hauv 250 ml flasks thiab 500 ml electrochemical iav hlwb nyob rau hauv aerobic mob ntawm 37 ° C.Nruab nrab muaj (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 SrBr30020, H. 008, 0.008 Na4F0H20PO.1.0 poov xab extract thiab 0.1 hlau citrate.Autoclave ntawm 121 ° C rau 20 min ua ntej inoculation.Sessile thiab planktonic hlwb raug suav nyob rau hauv lub teeb tsom iav siv lub hemocytometer ntawm 400x magnification.Thawj qhov concentration ntawm planktonic P. aeruginosa hlwb tam sim ntawd tom qab inoculation yog kwv yees li 106 hlwb / mL.
Electrochemical kev ntsuam xyuas tau ua nyob rau hauv ib tug classic peb-electrode iav cell nrog ib tug nruab nrab ntim ntawm 500 ml.Daim ntawv platinum thiab saturated calomel electrode (SCE) tau txuas nrog lub tshuab hluav taws xob los ntawm Luggin capillary uas muaj cov choj ntsev thiab ua haujlwm raws li cov txee thiab cov khoom siv hluav taws xob, raws li.Txhawm rau tsim cov khoom siv hluav taws xob ua haujlwm, cov roj hmab-coated tooj liab xaim tau txuas rau txhua tus qauv thiab coated nrog epoxy, tawm hauv thaj tsam li 1 cm2 ntawm ib sab rau kev ua haujlwm electrode.Thaum lub sij hawm ntsuas electrochemical, cov qauv tau muab tso rau hauv qhov nruab nrab 2216E thiab khaws cia ntawm qhov kub thiab txias (37 ° C) hauv dej da dej.OCP, LPR, EIS thiab cov ntaub ntawv muaj peev xwm dynamic polarization tau ntsuas siv Autolab potentiostat (Reference 600TM, Gamry Instruments, Inc., USA).Kev ntsuam xyuas LPR tau sau tseg ntawm qhov ntsuas ntsuas ntawm 0.125 mV s-1 hauv -5 thiab 5 mV ntau thiab Eocp nrog tus lej ntsuas ntawm 1 Hz.EIS tau ua nyob rau hauv lub xeev ruaj khov Eocp siv qhov kev siv hluav taws xob ntawm 5 mV nrog lub sinusoid ntau zaus ntawm 0.01 txog 10,000 Hz.Ua ntej lub peev xwm cheb, cov electrodes nyob rau hauv qhib Circuit Court hom kom txog rau thaum ib tug ruaj khov corrosion muaj peev xwm ntawm 42 tau mus txog.Nrog.Txhua qhov kev sim tau rov ua dua peb zaug nrog thiab tsis muaj Pseudomonas aeruginosa.
Cov qauv rau kev tsom xam metallographic tau mechanically polished nrog 2000 grit ntub SiC ntawv thiab tom qab ntawd polished nrog 0.05 µm Al2O3 hmoov slurry rau kev soj ntsuam kho qhov muag.Metallographic tsom xam tau ua los ntawm kev siv lub tshuab ntsuas qhov muag.Cov qauv yog etched nrog 10 wt% potassium hydroxide tov 43.
Tom qab incubation, ntxuav 3 zaug nrog phosphate buffered saline (PBS) (pH 7.4 ± 0.2) thiab kho nrog 2.5% (v/v) glutaraldehyde rau 10 teev los kho cov biofilm.Tom qab lub cev qhuav dej nrog ethanol nyob rau hauv ib tug stepped series (50%, 60%, 70%, 80%, 90%, 95% thiab 100% los ntawm ntim) ua ntej cua qhuav.Thaum kawg, ib zaj duab xis kub tau sputtered mus rau saum npoo ntawm cov qauv los muab cov conductivity rau SEM44 kev soj ntsuam.Cov duab SEM tau tsom mus rau qhov chaw nrog P. aeruginosa hlwb tshaj plaws nyob rau saum npoo ntawm txhua tus qauv.Kev tshuaj xyuas EMF tau ua tiav txhawm rau txheeb xyuas cov tshuaj lom neeg.Txhawm rau ntsuas qhov tob ntawm lub qhov, ib lub Zeiss confocal laser scanning microscope (CLSM) (LSM 710, Zeiss, Lub teb chaws Yelemees) tau siv.Txhawm rau soj ntsuam cov pits corrosion nyob rau hauv biofilm, cov qauv kuaj tau raug ntxuav ua ntej raws li Suav Teb Chaws Standard (CNS) GB / T4334.4-2000 kom tshem tawm cov khoom corrosion thiab biofilm los ntawm qhov chaw ntawm cov qauv kuaj.
X-ray photoelectron spectroscopy (XPS, ESCALAB250 Surface Analysis System, Thermo VG, USA) kev tsom xam siv lub monochromatic X-ray qhov chaw (Al Kα kab nrog lub zog ntawm 1500 eV thiab lub zog ntawm 150 W) nyob rau hauv ntau hom kev sib khi energies 0 hauv qab cov txheej txheem ntawm -1350 eV.Sau cov kev daws teeb meem siab siv 50 eV dhau lub zog thiab 0.2 eV kauj ruam loj.
Tshem tawm cov qauv incubated thiab maj mam ntxuav nws nrog PBS (pH 7.4 ± 0.2) rau 15 s45.Txhawm rau soj ntsuam cov kab mob muaj txiaj ntsig ntawm biofilm ntawm tus qauv, biofilm tau stained siv LIVE/DEAD BacLight Bacterial Viability Kit (Invitrogen, Eugene, OR, USA).Cov khoom siv muaj ob fluorescent dyes: SYTO-9 ntsuab fluorescent dye thiab propidium iodide (PI) liab fluorescent dye.Hauv CLSM, fluorescent ntsuab thiab liab dots sawv cev rau cov cell nyob thiab tuag, raws li.Rau staining, incubate 1 ml ntawm ib tug sib tov uas muaj 3 µl ntawm SYTO-9 thiab 3 µl ntawm PI tov ntawm chav tsev kub (23 ° C) nyob rau hauv qhov tsaus ntuj rau 20 feeb.Tom qab ntawd, cov qauv stained tau pom ntawm ob lub wavelengths (488 nm rau cov hlwb nyob thiab 559 nm rau cov hlwb tuag) siv Nikon CLSM apparatus (C2 Plus, Nikon, Nyiv).Ntsuas cov biofilm thickness hauv 3-D scanning hom.
Yuav ua li cas sau cov kab lus no: Li, H. et al.Cov nyhuv ntawm Pseudomonas aeruginosa marine biofilm ntawm microbial corrosion ntawm 2707 super duplex stainless hlau.kev tshawb fawb.Lub tsev 6, 20190;doi: 10.1038/srep20190 (2016).
Zanotto, F., Grassi, V., Balbo, A., Monticelli, C. & Zucchi, F. Stress corrosion cracking ntawm LDX 2101 duplex stainless hlau nyob rau hauv cov tshuaj chloride nyob rau hauv lub xub ntiag ntawm thiosulfate.corrosion.kev kawm.80, 205–212 (2014).
Kim, ST, Jang, SH, Lee, IS thiab Park, YS Cov nyhuv ntawm kev kho cua sov thiab nitrogen hauv shielding roj ntawm pitting corrosion kuj ntawm super duplex stainless hlau welds.corrosion.kev kawm.53, 1939–1947 (2011).
Shi, X., Avchi, R., Geyser, M. thiab Lewandowski, Z. Ib qho tshuaj sib piv kev kawm ntawm microbial thiab electrochemical pitting hauv 316L stainless hlau.corrosion.kev kawm.45, 2577–2595 (2003).
Luo H., Dong KF, Li HG thiab Xiao K. Electrochemical tus cwj pwm ntawm 2205 duplex stainless hlau nyob rau hauv alkaline daws ntawm ntau yam pH qhov tseem ceeb nyob rau hauv lub xub ntiag ntawm chloride.electrochemistry.Phau ntawv.64, 211–220 (2012).