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I-Microbial corrosion (MIC) yingxaki enkulu kumashishini amaninzi, njengoko inokukhokelela kwilahleko enkulu yezoqoqosho. I-Super duplex steel stainless 2707 (2707 HDSS) isetyenziswa kwiindawo zaselwandle ngenxa yokumelana kwayo neekhemikhali. Nangona kunjalo, ukuchasana kwayo ne-MIC akuboniswanga ngokomfuniselo. Olu phononongo luvavanye ukuziphatha kwe-MIC 2707 HDSS ebangelwa yibhaktheriya ye-aerobic yolwandle i-Pseudomonas aeruginosa. Uhlalutyo lwe-Electrochemical lubonise ukuba phambi kwe-Pseudomonas aeruginosa biofilm kwi-medium ye-2216E, utshintsho oluhle kwi-corrosion potential and ukwanda kwe-corrosion current density. Uhlalutyo lwe-X-ray ye-photoelectron spectroscopy (XPS) ibonise ukuhla komxholo we-Cr kumphezulu wesampuli phantsi kwe-biofilm. Uhlalutyo olubonakalayo lwemingxuma lubonise ukuba i-P. aeruginosa biofilm ivelise ubunzulu bomgodi obuyi-0.69 µm ngeentsuku ezili-14 zokufukamela. Nangona oku kuncinci, kubonisa ukuba i-2707 HDSS ayikhuselekanga ngokupheleleyo kwi-MIC ye-P. aeruginosa biofilms.
I-Duplex stainless steels (DSS) isetyenziswa ngokubanzi kumashishini ahlukeneyo ngenxa yokudibanisa okugqibeleleyo kweempawu ezibalaseleyo zoomatshini kunye nokumelana nokubola1,2. Nangona kunjalo, i-pitting yendawo isenzeka kwaye ichaphazela ingqibelelo yale steel3,4. I-DSS ayichasananga ne-microbial corrosion (MIC) 5,6. Nangona uluhlu olubanzi lwezicelo ze-DSS, kusekho iindawo apho ukuxhathisa ukubola kwe-DSS akwanelanga ukusetyenziswa kwexesha elide. Oku kuthetha ukuba kufuneka izixhobo ezibiza kakhulu ezinokumelana nomhlwa. UJeon et al7 ufumanise ukuba kwanezintsimbi ze-duplex ezingenasici (SDSS) zinezithintelo ezithile ngokwemiqathango yokuxhathisa umhlwa. Ke ngoko, kwezinye iimeko, iintsimbi ze-super duplex stainless (HDSS) ezinokumelana nokukhula okuphezulu ziyafuneka. Oku kwakhokelela ekuphuhlisweni kwe-HDSS ene-alloyed kakhulu.
Ukumelana nokubola kwe-DSS kuxhomekeke kumlinganiselo wezigaba ze-alpha kunye ne-gamma kwaye ziphelile kwiindawo ze-Cr, i-Mo kunye ne-W 8, i-9, i-10 kufuphi nesigaba sesibini. I-HDSS iqulethe umxholo ophezulu we-Cr, i-Mo kunye ne-N11, ngoko inokumelana nokugqwesa okugqwesileyo kunye nexabiso eliphezulu (45-50) lenombolo yokumelana ne-pitting elinganayo (PREN) enqunywe ngu-wt.% Cr + 3.3 (wt.% Mo + 0.5 wt. .% W) + 16% wt. N12. Ukumelana kwayo okugqwesileyo kokubola kuxhomekeke ekubunjweni kokulinganisela okuqulethe malunga ne-50% ye-ferritic (α) kunye ne-50% ye-austenitic (γ) izigaba. I-HDSS ineempawu ezingcono zoomatshini kunye nokuchasana okuphezulu kwi-chloride corrosion. Ukuphuculwa kokumelana nomhlwa kwandisa ukusetyenziswa kwe-HDSS kwiindawo ezinobundlongondlongo zekloride ezifana neendawo ezihlala elwandle.
Ii-MIC ziyingxaki enkulu kumashishini amaninzi afana ne-oyile negesi nemizi-mveliso yamanzi14. I-MIC yenza i-20% yawo wonke umonakalo owenziwe ngumhlwa15. I-MIC yi-corrosion ye-bioelectrochemical enokubonwa kwiindawo ezininzi. Iifilimu ze-Biofilm ezenza kwiindawo zetsimbi zitshintsha iimeko ze-electrochemical, ngaloo ndlela zichaphazela inkqubo yokubola. Kukholelwa ngokubanzi ukuba i-MIC corrosion yenziwa zii-biofilms. Iimicroorganisms ze-Electrogenic zitya iintsimbi ukuze zifumane amandla eziwadingayo ukuze ziphile17. Uphononongo lwamva nje lwe-MIC lubonise ukuba i-EET (i-extracellular electron transfer) yi-rate-limiting factor in MIC eyenziwa yi-electrogenic microorganisms. UZhang et al. I-18 ibonise ukuba i-electron intermediaries ikhawulezisa ukuhanjiswa kwee-electron phakathi kweeseli ze-Desulfovibrio sessificans kunye ne-304 yensimbi engenasici, okukhokelela kuhlaselo olubi kakhulu lwe-MIC. UAnning et al. 19 kunye noWenzlaff et al. I-20 ibonise ukuba i-biofilms ye-corrosive sulfate-reducing bacteria (SRBs) inokufunxa ngokuthe ngqo i-electrons kwii-substrates zetsimbi, okukhokelela kwi-pitting enzima.
I-DSS yaziwa ukuba ichaphazeleka kwi-MIC kumajelo eendaba aqukethe ii-SRBs, iibhaktheriya zokunciphisa isinyithi (IRBs), njl. Ezi bhaktheriya zibangela i-pitting yendawo kumphezulu we-DSS phantsi kwe-biofilms22,23. Ngokungafaniyo ne-DSS, i-HDSS24 MIC ayaziwa kakuhle.
I-Pseudomonas aeruginosa yintsholongwane ye-Gram-negative, eshukumayo, emile okwentonga esasazwe ngokubanzi kwindalo25. I-Pseudomonas aeruginosa ikwalelona qela le-microbial enkulu kwindawo yaselwandle, ebangela ukugxila okuphezulu kwe-MIC. I-Pseudomonas ibandakanyeka ngokusebenzayo kwinkqubo yokubola kwaye yamkelwa njenge-colonizer enguvulindlela ngexesha lokwenziwa kwe-biofilm. UMahat et al. 28 kunye Yuan et al. I-29 ibonise ukuba i-Pseudomonas aeruginosa ithambekele ekunyuseni izinga lokubola kwentsimbi epholileyo kunye ne-alloys kwiindawo ezihlala emanzini.
Injongo ephambili yalo msebenzi yayikukuphanda iipropati ze-MIC 2707 HDSS ezibangelwa yibhaktiriya ye-aerobic yolwandle i-Pseudomonas aeruginosa isebenzisa iindlela ze-electrochemical, iindlela zokuhlalutya umphezulu kunye nohlalutyo lwemveliso yokubola. Izifundo ze-Electrochemical, kubandakanywa amandla esekethe evulekileyo (i-OCP), ukuchasana kwe-polarization ye-linear (LPR), i-electrochemical impedance spectroscopy (EIS), kunye ne-polarization enamandla, zenziwa ukufunda ukuziphatha kwe-MIC 2707 HDSS. Uhlalutyo lwe-energy dispersive spectrometric (EDS) lwaqhutyelwa ukukhangela izinto zekhemikhali kumphezulu odlekileyo. Ukongezelela, i-X-ray photoelectron spectroscopy (XPS) yayisetyenziselwa ukumisela ukuzinza kwefilimu ye-oxide passivation phantsi kweempembelelo zendalo yaselwandle equkethe i-Pseudomonas aeruginosa. Ubunzulu bemingxuma bulinganiswe phantsi kwe-confocal laser scanning microscope (CLSM).
Itheyibhile 1 ibonisa ukubunjwa kweekhemikhali ze-2707 HDSS. Itheyibhile ye-2 ibonisa ukuba i-2707 HDSS ineempawu ezibalaseleyo zoomatshini kunye namandla esivuno se-650 MPa. Kwikhiwane. I-1 ibonisa i-microstructure ye-optical yesisombululo sobushushu esiphathwe nge-2707 HDSS. Kwi-microstructure equlethe malunga ne-50% ye-austenite kunye ne-50% yezigaba ze-ferrite, iibhendi ezinde ze-austenite kunye ne-ferrite ngaphandle kwezigaba zesibini ziyabonakala.
Kwikhiwane. I-2a ibonisa amandla esekethe evulekileyo (Eocp) ngokubhekiselele kwixesha lokuvezwa kwe-2707 HDSS kwi-2216E abiotic medium kunye ne-P. aeruginosa umhluzi weentsuku ze-14 kwi-37 ° C. Ibonisa ukuba utshintsho olukhulu nolubalulekileyo kwi-Eocp lwenzeka kwiiyure ezingama-24 zokuqala. Amaxabiso e-Eocp kuzo zombini iimeko aphakamileyo kwi--145 mV (xa kuthelekiswa ne-SCE) malunga ne-16 h kwaye emva koko yehla ngokukhawuleza, ifikelela -477 mV (xa kuthelekiswa ne-SCE) kunye -236 mV (xa kuthelekiswa ne-SCE) yesampuli ye-abiotic. kunye neekhuphoni zeP Pseudomonas aeruginosa, ngokulandelanayo). Emva kweeyure ze-24, ixabiso le-Eocp 2707 HDSS ye-P. aeruginosa yayizinzile kwi--228 mV (xa kuthelekiswa ne-SCE), ngelixa ixabiso elihambelanayo leesampuli ezingezizo zebhayoloji lalimalunga -442 mV (xa kuthelekiswa ne-SCE). I-Eocp kubukho be-P. aeruginosa yayiphantsi kakhulu.
Uphononongo lwe-Electrochemical yeesampulu ze-HDSS ezingama-2707 kwi-abiotic medium kunye ne-Pseudomonas aeruginosa umhluzi kwi-37 °C:
(a) I-Eocp njengomsebenzi wexesha lokuvezwa, (b) iigophe zepolarization ngosuku lwe-14, (c) Rp njengomsebenzi wexesha lokuvezwa, kunye (d) ne-icorr njengomsebenzi wexesha lokuvezwa.
Itheyibhile 3 ibonisa imilinganiselo ye-electrochemical corrosion ye-2707 HDSS iisampulu ezivezwe kwi-abiotic kunye ne-Pseudomonas aeruginosa yeendaba ezifakwe kwi-inoculated kwithuba leentsuku ze-14. I-tangents ye-anode kunye ne-cathode curves yakhutshwa ukuze ifumane i-intersections enika i-corrosion current density (icorr), i-corrosion potential (Ecorr) kunye ne-Tafel slope (βα kunye ne-βc) ngokweendlela eziqhelekileyo30,31.
Njengoko kubonisiwe kwifig. I-2b, ukunyuka okuphezulu kwi-curve ye-P. aeruginosa kubangele ukwanda kwe-Ecorr xa kuthelekiswa ne-abiotic curve. Ixabiso le-icorr, elilingana nezinga lokubola, linyuke laya kutsho kwi-0.328 µA cm-2 kwisampulu ye-Pseudomonas aeruginosa, ephindwe kane kunesampulu engeyoyebhayoloji (0.087 µA cm-2).
I-LPR yindlela yakudala engonakalisi ye-electrochemical yokuhlalutya umhlwa okukhawulezayo. Ikwasetyenziselwa ukufunda i-MIC32. Kwikhiwane. I-2c ibonisa ukuchasana kwe-polarization (Rp) njengomsebenzi wexesha lokuvezwa. Ixabiso eliphezulu le-Rp lithetha ukuthotywa okuncinci. Kwiiyure ezingama-24 zokuqala, i-Rp 2707 HDSS yafikelela kwi-1955 kΩ cm2 kwimizekelo ye-abiotic kunye ne-1429 kΩ cm2 kwisampulu ze-Pseudomonas aeruginosa. Umzobo 2c ubonisa ukuba ixabiso le-Rp lehle ngokukhawuleza emva kosuku olunye kwaye lahlala lingaguqukanga kwiintsuku ze-13 ezilandelayo. Ixabiso le-Rp lesampulu ye-Pseudomonas aeruginosa imalunga ne-40 kΩ cm2, engaphantsi kakhulu kunexabiso le-450 kΩ cm2 yesampulu engeyoyebhayoloji.
Ixabiso le-icorr lilingana nezinga lokutya okufanayo. Ixabiso layo lingabalwa kule equation yeStern-Giri ilandelayo:
Ngokutsho kukaZoe et al. 33, ixabiso eliqhelekileyo lethambeka le-Tafel B kulo msebenzi lithathwe libe yi-26 mV/dec. Umzobo we-2d ubonisa ukuba i-icorr yesampula engeyiyo yebhayoloji ye-2707 yahlala izinzile, ngelixa isampuli ye-P. aeruginosa iguquguquka kakhulu emva kweeyure zokuqala ze-24. Amaxabiso e-icorr eisampulu ze-P. aeruginosa ibingumyalelo wobukhulu obuphezulu kunolawulo olungelulo lwebhayoloji. Lo mkhwa uhambelana neziphumo zokumelana ne-polarization.
I-EIS yenye indlela engonakalisiyo esetyenziselwa ukubonakalisa ukusabela kwe-electrochemical kwi-corrod surfaces. I-Impedance spectra kunye nexabiso le-capacitance elibaliweyo leisampulu ezivezwe kwindawo ye-abiotic kunye nesisombululo se-Pseudomonas aeruginosa, ifilimu engabonakaliyo / i-biofilm ukumelana ne-Rb eyenziwe kumphezulu wesampulu, ukuchasana nokudluliselwa kwe-Rct, i-Cdl yombane ephindwe kabini (EDL) kunye neeparamitha zeSigaba se-QCPE (CPE). Ezi parameters zahlaziywa ngakumbi ngokufaka idatha kusetyenziswa imodeli yesekethe elinganayo (EEC).
Kwikhiwane. I-3 ibonisa iindawo eziqhelekileyo zeNyquist (a kunye ne-b) kunye neendawo zeBode (a' kunye ne-b') ze-2707 iisampuli ze-HDSS kwi-abiotic media kunye ne-P. aeruginosa umhluzi wamaxesha ahlukeneyo okufukamela. Idayamitha yeringi yeNyquist iyancipha xa kukho iPseudomonas aeruginosa. Isakhiwo seBode (Umfanekiso 3b ') ubonisa ukwanda kwe-impedance epheleleyo. Ulwazi malunga nexesha lokuphumla elingaguqukiyo linokufumaneka kwi-phase maxima. Kwikhiwane. I-4 ibonisa izakhiwo ezibonakalayo ezisekelwe kwi-monolayer (a) kunye ne-bilayer (b) kunye nee-EEC ezihambelanayo. I-CPE yaziswa kwimodeli ye-EEC. Ukwamkelwa kwayo kunye nokuphazamiseka kubonakaliswa ngolu hlobo lulandelayo:
Iimodeli ezimbini zomzimba kunye neesekethe ezilinganayo zokulinganisa i-impedance spectrum yesampuli ye-2707 HDSS:
apho u-Y0 lixabiso le-KPI, j linani lentelekelelo okanye (-1)1/2, ω yi-angular frequency, n sisalathiso samandla e-KPI esingaphantsi kwe-135. I-inversion yokumelana nokudluliselwa kwentlawulo (okt 1 / Rct) ihambelana nezinga lokubola. I-Rct encinci, iphezulu izinga lokutya27. Emva kweentsuku ze-14 zokufukamela, i-Rct ye-Pseudomonas aeruginosa iisampulu ifikelele kwi-32 kΩ cm2, engaphantsi kakhulu kwe-489 kΩ cm2 yeesampuli ezingezona zebhayoloji (Itheyibhile 4).
Imifanekiso ye-CLSM kunye nemifanekiso ye-SEM kwi-Figure 5 ibonisa ngokucacileyo ukuba i-biofilm yokugqoka ebusweni be-HDSS isampuli ye-2707 emva kweentsuku ze-7 inzima. Nangona kunjalo, emva kweentsuku ezili-14, ukukhutshwa kwe-biofilm kwakungalunganga kwaye ezinye iiseli ezifileyo zavela. Itheyibhile yesi-5 ibonisa ubukhulu be-biofilm kwiisampuli ze-2707 HDSS emva kokuvezwa kwi-P. aeruginosa iintsuku ezi-7 kunye ne-14. Ubuninzi bebhayofilm ubukhulu butshintshile ukusuka kwi-23.4 µm emva kweentsuku ezisi-7 ukuya kwi-18.9 µm emva kweentsuku ezili-14. Umndilili wobunzima bebhayofilm nawo ubuqinisekisile lo mkhwa. Yehla ukusuka kwi-22.2 ± 0.7 μm emva kweentsuku ezi-7 ukuya kwi-17.8 ± 1.0 μm emva kweentsuku ezili-14.
(a) Umfanekiso we-3-D CLSM ngeentsuku ezisi-7, (b) umfanekiso we-3-D CLSM ngeentsuku ezili-14, (c) umfanekiso we-SEM ngeentsuku ezisi-7, kunye (d) nomfanekiso we-SEM ngeentsuku ezili-14.
I-EMF iveze izinto zekhemikhali kwi-biofilms kunye neemveliso zomhlwa kwiisampuli ezivezwe kwi-P. aeruginosa iintsuku ezili-14. Kwikhiwane. Umzobo we-6 ubonisa ukuba umxholo we-C, N, O, kunye ne-P kwi-biofilms kunye neemveliso ze-corrosion ziphezulu kakhulu kunezinyithi ezicocekileyo, ekubeni ezi zinto zidibene ne-biofilms kunye ne-metabolites yazo. Iintsholongwane zifuna kuphela isixa sechromium kunye nentsimbi. Amanqanaba aphezulu e-Cr kunye ne-Fe kwi-biofilm kunye neemveliso ze-corrosion kumphezulu weesampuli zibonisa ukuba i-matrix yensimbi ilahlekelwe yizinto ngenxa yokubola.
Emva kweentsuku ezili-14, imingxuma ene-P. aeruginosa nangaphandle kwayo yabonwa phakathi kwe-2216E. Ngaphambi kokufukanyelwa, umphezulu weesampulu wawugudileyo kwaye awunasiphako (umzobo 7a). Emva kokufakwa kunye nokususwa kwe-biofilm kunye nemveliso ye-corrosion, imingxuma enzulu kumphezulu weesampuli ihlolwe kusetyenziswa i-CLSM, njengoko kubonisiwe kwi-Fig. 7b kunye ne-c. Akukho mgodi ucacileyo ufunyenwe kumphezulu wolawulo olungelulo lwebhayoloji (obona nzulu bomgodi yi-0.02 µm). Obona bukhulu bomngxuma ubunzulu obubangelwe yi-P. aeruginosa yi-0.52 µm ngeentsuku ezisi-7 kunye ne-0.69 µm ngeentsuku ezili-14, ngokusekwe kumndilili wobunzulu bomngxuma obuphezulu kwiisampulu ezi-3 (i-10 ubunzulu bomngxuma obona buninzi bakhethwa kwisampulu nganye). Impumelelo ye-0.42 ± 0.12 µm kunye ne-0.52 ± 0.15 µm, ngokulandelanayo (Itheyibhile 5). Ezi xabiso zobunzulu bomngxuma zincinci kodwa zibalulekile.
(a) phambi kokuba sesichengeni, (b) iintsuku ezili-14 kwindawo yendalo ephilayo, kunye (c) neentsuku ezili-14 kwi-Pseudomonas aeruginosa broth.
Kwikhiwane. Itheyibhile 8 ibonisa i-spectra ye-XPS yeesampulu ezahlukeneyo, kwaye ukubunjwa kweekhemikhali ezihlalutyelwe kwindawo nganye kushwankathelwa kwiThebhile 6. KwiThebhile 6, iipesenti ze-athomu ze-Fe kunye ne-Cr phambi kwe-P. aeruginosa (iisampulu A kunye ne-B) zaziphantsi kakhulu kunezo zolawulo olungezona izinto eziphilayo. (iisampulu C kunye no-D). Kwisampuli ye-P. aeruginosa, i-spectral curve kwinqanaba le-nucleus ye-Cr 2p ifakwe kumacandelo amane aphezulu kunye namandla okubopha (BE) ye-574.4, 576.6, 578.3 kunye ne-586.8 eV, enokuthi ifakwe kwi-Cr, CrO3, CrO3, CrO3. kunye ne-Cr(OH)3, ngokulandelelanayo (Umfanekiso 9a kunye no-b). Kwiisampuli ezingezizo zebhayoloji, i-spectrum yenqanaba eliphambili le-Cr 2p liqulethe iincopho ezimbini eziphambili ze-Cr (573.80 eV ye-BE) kunye ne-Cr2O3 (575.90 eV ye-BE) kwiiFig. 9c kunye no-d, ngokulandelelanayo. Owona mahluko umangalisayo phakathi kweesampulu ze-abiotic kunye neesampulu ze-P. aeruginosa yaba bubukho be-Cr6+ kunye nomlinganiselo ophezulu ozalanayo we-Cr(OH)3 (BE 586.8 eV) phantsi kwe-biofilm.
I-spectra ye-XPS ebanzi yobuso besampula ye-2707 HDSS kwimidiya emibini yi-7 kunye neentsuku ze-14, ngokulandelanayo.
(a) Iintsuku ezisi-7 zokuchanabeka kwi-P. aeruginosa, (b) iintsuku ezili-14 zokuchanabeka kwi-P. aeruginosa, (c) iintsuku ezisi-7 kwindawo ye-abiotic, kunye (d) neentsuku ezili-14 kwindawo ye-abiotic.
I-HDSS ibonisa umgangatho ophezulu wokumelana nokubola kwiindawo ezininzi. UKim et al.2 wabika ukuba i-HDSS UNS S32707 ichongiwe njenge-DSS ene-alloyed kakhulu kunye ne-PREN enkulu kune-45. Ixabiso le-PREN yesampuli ye-2707 HDSS kulo msebenzi yayingu-49. Oku kubangelwa umxholo ophezulu we-chromium kunye nomxholo ophezulu we-molybdenum kunye ne-nickel, eziluncedo kwiindawo ezine-acidic. kunye nokusingqongileyo okunomxholo ophezulu wekloridi. Ukongezelela, ukubunjwa okunokulinganisela kunye ne-microstructure engenasiphako kunenzuzo yokuzinza kwesakhiwo kunye nokumelana nokubola. Nangona kunjalo, nangona i-chemical resistance resistance, idatha yovavanyo kulo msebenzi ibonisa ukuba i-2707 HDSS ayikhuselekanga ngokupheleleyo kwi-P. aeruginosa biofilm MICs.
Iziphumo ze-Electrochemical zibonise ukuba izinga lokubola kwe-2707 HDSS kwi-P. aeruginosa umhluzi wenyuka kakhulu emva kweentsuku ze-14 xa kuthelekiswa nendawo engeyiyo yezinto eziphilayo. Kwi-Figure 2a, ukuncipha kwe-Eocp kwabonwa kokubili kwi-abiotic medium kunye ne-P. aeruginosa umhluzi kwiiyure ezingama-24 zokuqala. Emva koko, i-biofilm igubungela ngokupheleleyo umphezulu wesampuli, kwaye i-Eocp iyazinza36. Nangona kunjalo, inqanaba le-Eocp yebhayoloji laliphezulu kakhulu kunenqanaba le-Eocp engeyiyo eyebhayoloji. Kukho izizathu zokukholelwa ukuba lo mahluko unxulumene nokusekwa kwe-P. aeruginosa biofilms. Kwikhiwane. I-2d phambi kwe-P. aeruginosa, i-icorr 2707 ixabiso le-HDSS lifikelele kwi-0.627 μA cm-2, elingumyalelo wobukhulu obuphezulu kunolawulo lwe-abiotic (0.063 μA cm-2), eyayihambelana nexabiso le-Rct elilinganiswe yi-EIS. Kwiintsuku ezimbalwa zokuqala, ixabiso le-impedance kwi-P. aeruginosa broth liye lanyuka ngenxa yokuncamathela kweeseli ze-P. aeruginosa kunye nokwakhiwa kwee-biofilms. Nangona kunjalo, xa i-biofilm igubungela ngokupheleleyo umphezulu wesampulu, i-impedance iyancipha. Uluhlu olukhuselayo luhlaselwa ngokuyinhloko ngenxa yokubunjwa kwe-biofilms kunye ne-biofilm metabolites. Ngenxa yoko, ukuxhathisa kwe-corrosion yehla ngokuhamba kwexesha kwaye uncamathiselo lwe-P. aeruginosa lubangele ukubola kwendawo. Iindlela zokusingqongileyo ze-abiotic zazahlukile. Ukuxhatshazwa kwe-corrosion ye-non-biological control yayiphezulu kakhulu kunexabiso elihambelanayo leesampuli ezivezwe kwi-P. aeruginosa broth. Ukongeza, kwi-abiotic accessions, ixabiso le-Rct 2707 HDSS lifikelele kwi-489 kΩ cm2 ngosuku lwe-14, eliphindwe ngama-15 ngaphezu kwexabiso le-Rct (32 kΩ cm2) phambi kwe-P. aeruginosa. Ngaloo ndlela, i-2707 HDSS inokumelana ne-corrosion egqwesileyo kwindawo eyinyumba, kodwa ayixhathisi kwi-MICs evela kwi-P. aeruginosa biofilms.
Ezi ziphumo zinokujongwa kwakhona kwi-polarization curves kwiFig. 2b. I-Anodic branching iye yadibaniswa ne-Pseudomonas aeruginosa ukubunjwa kwe-biofilm kunye ne-metal oxidation reactions. Kule meko, ukusabela kwe-cathodic kukunciphisa i-oxygen. Ubukho be-P. aeruginosa bandise kakhulu ubuninzi be-corrosion yangoku, malunga nomyalelo wobukhulu obuphezulu kunolawulo lwe-abiotic. Oku kubonisa ukuba i-P. aeruginosa biofilm iphucula i-corrosion yendawo ye-2707 HDSS. U-Yuan et al.29 wafumanisa ukuba ubuninzi be-corrosion yangoku ye-Cu-Ni 70/30 ingxubevange yenyuka phantsi kwesenzo se-P. aeruginosa biofilm. Oku kunokuba ngenxa ye-biocatalysis yokunciphisa i-oksijini nge-Pseudomonas aeruginosa biofilms. Olu qwalaselo lunokucacisa kwakhona i-MIC 2707 HDSS kulo msebenzi. Kusenokubakho ioksijini encinci phantsi kwe-aerobic biofilms. Ngoko ke, ukwala ukuphinda udlulise i-metal surface nge-oksijeni ingaba yinto ebangela i-MIC kulo msebenzi.
UDickinson et al. I-38 icebise ukuba ireyithi yeekhemikhali kunye ne-electrochemical reactions inokuchaphazeleka ngokuthe ngqo ngumsebenzi we-metabolic we-sessile ibhaktiriya kumphezulu wesampulu kunye nohlobo lweemveliso zokubola. Njengoko kuboniswe kwi-Figure 5 kunye neThebhile 5, inani leeseli kunye ne-biofilm ubukhulu behla emva kweentsuku ze-14. Oku kunokuchazwa ngokufanelekileyo kukuba emva kweentsuku ezili-14, uninzi lweeseli ze-sessile kumphezulu we-2707 HDSS zafa ngenxa yokuncipha kwezondlo kwi-2216E medium okanye ukukhutshwa kwee-ion zesinyithi ezinetyhefu kwi-matrix ye-2707 HDSS. Lo ngumda wemifuniselo yebhetshi.
Kulo msebenzi, i-P. aeruginosa biofilm ibe negalelo ekunciphiseni kwendawo ye-Cr kunye ne-Fe phantsi kwe-biofilm ebusweni be-2707 HDSS (Umfanekiso 6). Itheyibhile ye-6 ibonisa ukunciphisa i-Fe kunye ne-Cr kwisampula D xa kuthelekiswa nesampuli C, ebonisa ukuba i-Fe kunye ne-Cr echithiweyo ebangelwa yi-P. aeruginosa biofilm iqhubekile kwiintsuku zokuqala ze-7. Imo engqongileyo ye-2216E isetyenziselwa ukulinganisa imeko-bume yaselwandle. Iqulethe i-17700 ppm Cl-, ethelekiseka nomxholo wayo kumanzi endalo olwandle. Ubukho be-17700 ppm Cl- yayisisizathu esiphambili sokuhla kwe-Cr kwiisampuli ze-abiotic ze-7 kunye ne-14 yeentsuku ezihlalutywe yi-XPS. Xa kuthelekiswa neesampuli ze-P. aeruginosa, ukuchithwa kwe-Cr kwiisampulu ze-abiotic kwakungaphantsi kakhulu ngenxa yokumelana okunamandla kwe-2707 HDSS kwi-chlorine phantsi kweemeko ze-abiotic. Kwikhiwane. I-9 ibonisa ubukho be-Cr6 + kwifilimu edlulayo. Inokubandakanyeka ekukhutshweni kwe-chromium kwiindawo zensimbi nge-P. aeruginosa biofilms, njengoko kucetyiswe nguChen noClayton.
Ngenxa yokukhula kwebhaktheriya, amaxabiso e-pH aphakathi ngaphambi nasemva kokulima ayeyi-7.4 kunye ne-8.2, ngokulandelelanayo. Ngaloo ndlela, ngaphantsi kwe-P. aeruginosa biofilm, i-organic acid corrosion ayinakwenzeka ukuba ibe negalelo kulo msebenzi ngenxa ye-pH ephezulu kwi-bulk medium. I-pH ye-non-biological control medium ayizange itshintshe kakhulu (ukusuka kwi-7.4 yokuqala ukuya kwi-7.5 yokugqibela) ngexesha lovavanyo lweentsuku ezili-14. Ukunyuka kwe-pH kwindawo yembewu emva kokufukanyelwa kubangelwe ngumsebenzi we-metabolic we-P. aeruginosa kwaye kwafunyaniswa ukuba unempembelelo efanayo kwi-pH ngokungabikho kwemicu yovavanyo.
Njengoko kubonisiwe kuMfanekiso 7, obona bukhulu bomngxuma ubunzulu obubangelwa yi-P. aeruginosa biofilm yayiyi-0.69 µm, inkulu kakhulu kunobo be-abiotic medium (0.02 µm). Oku kuhambelana nedatha ye-electrochemical echazwe ngasentla. Ubunzulu bomgodi we-0.69 µm bungaphezulu kokuphindwe kashumi encinci kune-9.5 µm ixabiso elibikwe nge-2205 DSS phantsi kweemeko ezifanayo. Ezi datha zibonisa ukuba i-2707 HDSS ibonisa ukuchasana okungcono kwi-MIC kune-2205 DSS. Oku akufuneki kusimangalise kuba i-2707 HDSS inamanqanaba aphezulu e-Cr abonelela ngokudlula ixesha elide, kunzima kakhulu ukukhupha i-P. aeruginosa, kwaye ngenxa yesakhiwo sayo sesigaba esilungeleleneyo ngaphandle kwemvula yesibini eyingozi ibangela ukugoba.
Ukuqukumbela, imigodi ye-MIC ifunyenwe phezu kwe-2707 HDSS kwi-P. aeruginosa broth xa kuthelekiswa nemigodi engabalulekanga kwindawo ye-abiotic. Lo msebenzi ubonisa ukuba i-2707 HDSS inokuchasana okungcono kwi-MIC kune-2205 DSS, kodwa ayikhuselekanga ngokupheleleyo kwi-MIC ngenxa ye-P. aeruginosa biofilm. Ezi ziphumo zinceda ekukhetheni iintsimbi eziziintsimbi ezifanelekileyo kunye neminyaka elindelekileyo yokuphila kwendalo yaselwandle.
Ikhuphoni ye-2707 HDSS enikezelwa yiYunivesithi yaseMntla-mpuma (NEU) yeSikolo seMetallurgy eShenyang, eChina. Ukubunjwa kwe-elemental ye-2707 HDSS kuboniswe kwiThebhile 1, eyahlalutywa yi-NEU yoHlalutyo lweMathiriyeli kunye neSebe loVavanyo. Zonke iisampuli zaphathwa isisombululo esiqinileyo kwi-1180 ° C ngeyure eli-1. Phambi kovavanyo lomhlwa, i-2707 HDSS emile okwengqekembe enendawo ephezulu evulekileyo ye-1 cm2 yapolishwa yaya kutsho kwi-2000 grit nge-silicon carbide sandpaper emva koko yapolishwa nge-0.05 µm Al2O3 powder slurry. Amacala kunye nezantsi zikhuselwe ngepeyinti ye-inert. Emva kokumisa, iisampulu zihlanjwe ngamanzi angcolileyo ahlambulukileyo kwaye zihlanjululwe nge-75% (v / v) ye-ethanol ye-0.5 h. Emva koko zomiswa emoyeni phantsi kokukhanya kwe-ultraviolet (UV) i-0.5 h phambi kokusetyenziswa.
I-Marine Pseudomonas aeruginosa strain MCCC 1A00099 yathengwa kwi-Xiamen Marine Culture Collection Centre (MCCC), China. I-Pseudomonas aeruginosa yakhuliswa phantsi kweemeko ze-aerobic kwi-37 ° C. kwiiflaski ze-250 ml kunye ne-500 ml yeglasi yeeseli ze-electrochemical zisebenzisa i-Marine 2216E liquid medium (Qingdao Hope Biotechnology Co., Ltd., Qingdao, China). Eliphakathi liqulathe (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, 202 H0Br. I-NaSiO3, 0016 6NH26NH3, 3.0016 NH3 5.0 peptone, i-1.0 yeast extract kunye ne-0.1 citrate yensimbi. I-Autoclave kwi-121 ° C imizuzu engama-20 ngaphambi kokugonywa. Bala i-sessile kunye neeseli zeplanktonic ezine-hemocytometer phantsi kwe-microscope yokukhanya kwi-400x yokukhulisa. Ukuxinwa kokuqala kweplanktonic Pseudomonas aeruginosa ngokukhawuleza emva kokugonywa kwakumalunga neeseli ze-106 / ml.
Iimvavanyo ze-Electrochemical zenziwa kwi-classic yeglasi ye-electrode emithathu kunye nomthamo ophakathi kwe-500 ml. Iphepha leplatinum kunye ne-saturated calomel electrode (SAE) zixhunywe kwi-reactor ngokusebenzisa i-Luggin capillaries ezaliswe ngamabhuloho etyuwa, asebenza njenge-counter and reference electrode, ngokulandelanayo. Ukwenziwa kwee-electrodes ezisebenzayo, ucingo lwe-rubberized copper lufakwe kwisampuli nganye kwaye lugqunywe nge-epoxy resin, lushiya malunga ne-1 cm2 yendawo engakhuselekanga ye-electrode esebenzayo kwelinye icala. Ngexesha lokulinganisa i-electrochemical, iisampuli zifakwe kwi-2216E medium kwaye zigcinwe kwiqondo lokushisa eliqhubekayo (37 ° C) kwindawo yokuhlambela amanzi. I-OCP, i-LPR, i-EIS kunye nedatha ye-polarization enokubakho ilinganiswa kusetyenziswa i-Autolab potentiostat (Reference 600TM, Gamry Instruments, Inc., USA). Iimvavanyo ze-LPR zirekhodwe kwireyithi ye-scan ye-0.125 mV s-1 kuluhlu lwe-5 ukuya kwi-5 mV kunye ne-Eocp kunye nesantya sesampuli ye-1 Hz. I-EIS yenziwa nge-sine wave ngaphaya koluhlu lwamaza e-0.01 ukuya kwi-10,000 Hz kusetyenziswa i-voltage esetyenzisiweyo ye-5 mV kwindawo ezinzileyo ye-Eocp. Ngaphambi kokutshayela okunokwenzeka, i-electrodes yayikwimowudi engasebenziyo de kube ixabiso elizinzileyo le-corrosion potential free lifikelelwe. Iingqungquthela ze-polarization zaye zalinganiswa ukusuka -0.2 ukuya kwi-1.5 V njengomsebenzi we-EoCP kwizinga lokuskena kwe-0.166 mV / s. Uvavanyo ngalunye luphindwe ngamaxesha e-3 kunye nangaphandle kwe-P. aeruginosa.
Iisampulu zohlalutyo lwe-metallographic zapholishwa ngomatshini ngephepha le-SiC legrit elimanzi le-2000 kwaye emva koko yapolishwa nge-0.05 µm Al2O3 yomgubo wokunqunyanyiswa ukuze kuqwalaselwe amehlo. Uhlalutyo lwe-metallographic lwenziwa kusetyenziswa i-microscope ebonakalayo. Iisampuli zifakwe nge-10 wt% isisombululo se-potassium hydroxide 43.
Emva kokufukanyelwa, iisampulu zahlanjwa amaxesha e-3 nge-phosphate buffered saline (PBS) (pH 7.4 ± 0.2) emva koko zilungiswe nge-2.5% (v/v) glutaraldehyde iiyure ezili-10 ukulungisa i-biofilms. Emva koko yachithwa nge-ethanol edibeneyo (50%, 60%, 70%, 80%, 90%, 95% kunye ne-100% ngevolumu) ngaphambi kokumisa umoya. Ekugqibeleni, ifilimu yegolide ifakwe kumphezulu wesampulu ukubonelela nge-conductivity yokujongwa kwe-SEM. Imifanekiso ye-SEM yayigxininise kumabala aneeseli ezininzi ze-P. aeruginosa kumphezulu wesampuli nganye. Yenza uhlalutyo lwe-EDS ukufumana izinto zekhemikhali. I-Zeiss confocal laser scanning microscope (CLSM) (LSM 710, Zeiss, Germany) yasetyenziswa ukulinganisa ubunzulu bomgodi. Ukuqwalasela imigodi ye-corrosion phantsi kwe-biofilm, isampuli yovavanyo yaqala ukucocwa ngokwe-Chinese National Standard (CNS) GB/T4334.4-2000 ukususa iimveliso ze-corrosion kunye ne-biofilm kumphezulu wesampuli yovavanyo.
I-X-ray photoelectron spectroscopy (i-XPS, i-ESCALAB250 inkqubo yohlalutyo lomphezulu, i-Thermo VG, e-USA) uhlalutyo lwenziwa kusetyenziswa umthombo we-X-ray we-monochromatic (umgca we-Aluminium Kα onamandla we-1500 eV kunye namandla e-150 W) kuluhlu olubanzi lwamandla okubopha i-0 phantsi kweemeko eziqhelekileyo ze -1350 eV. I-spectra yesisombululo esiphezulu sirekhodwe kusetyenziswa amandla okuhambisa i-50 eV kunye nesinyathelo se-0.2 eV.
Iisampuli ezifakwe kwi-incubated zisusiwe kwaye zahlanjwa ngobumnene nge-PBS (pH 7.4 ± 0.2) kwi-15 s45. Ukujonga ukusebenza kwebhaktheriya yee-biofilms kwiisampulu, ii-biofilms zangcoliswa kusetyenziswa i-LIVE/DEAD BacLight Bacterial Viability Kit (Invitrogen, Eugene, OR, USA). Ikhithi iqulethe iidayi ezimbini ze-fluorescent: I-SYTO-9 ye-fluorescent eluhlaza kunye ne-propidium iodide (PI) idayi ebomvu ye-fluorescent. Kwi-CLSM, amachaphaza aluhlaza kunye nebomvu e-fluorescent amele iiseli eziphilayo nezifileyo, ngokulandelanayo. Ukucoca, i-1 ml yomxube oqulethe i-3 µl ye-SYTO-9 kunye ne-3 µl yesisombululo se-PI yafukanyelwa imizuzu engama-20 kwiqondo lobushushu begumbi (23°C) ebumnyameni. Emva koko, iisampuli ezinamabala zavavanywa kumaza amabini (488 nm kwiiseli eziphilayo kunye ne-559 nm yeeseli ezifileyo) kusetyenziswa i-Nikon CLSM apparatus (C2 Plus, Nikon, Japan). Ubunzima be-biofilm bulinganiswe kwimowudi yokuskena ye-3D.
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