Ka hopena o Pseudomonas aeruginosa Marine Biofilm ma ka Microbial Corrosion o 2707 Super Duplex Stainless Steel

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Hōʻike i kahi carousel o ʻekolu paheʻe i ka manawa hoʻokahi.E hoʻohana i nā pihi Mua a me Next no ka neʻe ʻana i ʻekolu paheʻe i ka manawa, a i ʻole e hoʻohana i nā pihi paheʻe ma ka hopena e neʻe i ʻekolu mau paheʻe i ka manawa.
ʻO ka microbial corrosion (MIC) kahi pilikia nui i nā ʻoihana he nui no ka mea hiki ke alakaʻi i nā poho waiwai nui.Hoʻohana ʻia ʻo Super duplex stainless steel 2707 (2707 HDSS) i nā kaiapuni kai ma muli o kona kūpaʻa kemika maikaʻi loa.Eia naʻe, ʻaʻole i hōʻike ʻia kona kūʻē ʻana iā MIC.Ua nānā kēia haʻawina i ka ʻano o MIC 2707 HDSS i hoʻokumu ʻia e ka marine aerobic bacterium Pseudomonas aeruginosa.Electrochemical kālailai hōʻike i ke alo o ka Pseudomonas aeruginosa biofilm i loko o ka 2216E medium, i ka corrosion hiki ke hoʻololi maikaʻi, a me ka corrosion kēia manawa māhuahua.Ua hōʻike nā hopena o ka X-ray photoelectron spectroscopy (XPS) i ka emi ʻana o ka maʻiʻo Cr ma ka ʻaoʻao hāpana ma lalo o ka biofilm.Ua hōʻike ʻia ka ʻike ʻana o nā kiʻi lua i hana ʻia nā biofilms Pseudomonas aeruginosa i ka hohonu o ka lua he 0.69 µm ma hope o 14 mau lā o ka moʻomeheu.ʻOiai he mea liʻiliʻi kēia, hōʻike ʻia ʻaʻole pale loa ʻo 2707 HDSS i nā hopena o nā biofilm P. aeruginosa ma MIC.
Hoʻohana nui ʻia ka Duplex stainless steel (DSS) i nā ʻoihana like ʻole ma muli o ka hui maikaʻi ʻana o nā waiwai mechanical maikaʻi loa a me ke kūpaʻa corrosion1,2.Eia nō naʻe, hiki ke hoʻokō ʻia ka lua kūloko, hiki ke hoʻopilikia i ka pono o kēia kila 3, 4.ʻAʻole pale ʻia ka DSS mai ka microbial corrosion (MIC)5,6.ʻOiai ʻo ka laulā noiʻi o DSS he ākea loa, aia nō nā kaiapuni kahi i lawa ʻole ai ke kūpaʻa corrosion o DSS no ka hoʻohana lōʻihi.ʻO ia hoʻi, pono nā mea kūʻai nui me ke kūpaʻa corrosion kiʻekiʻe.Ua ʻike ʻo Jeon et al.7 ʻoiai ʻo ka super duplex stainless steel (SDSS) kekahi mau palena i ke ʻano o ka pale ʻana i ka corrosion.No laila, pono ka super duplex stainless steels (HDSS) me ke kūpaʻa corrosion kiʻekiʻe ma kekahi mau noi.Ua alakaʻi kēia i ka hoʻomohala ʻana o ka HDSS i hoʻohui ʻia.
Hoʻoholo ʻia ke kūpaʻa corrosion o DSS e ka ratio o ka α-phase i ka γ-phase a me nā wahi i hoʻopau ʻia ma Cr, Mo a me W e pili ana i nā pae lua8,9,10.Loaʻa i ka HDSS kahi maʻiʻo kiʻekiʻe o Cr, Mo a me N11, e hāʻawi iā ia i ke kūpaʻa corrosion maikaʻi loa a me ka waiwai kiʻekiʻe (45-50) equivalent pitting resistance value (PREN), i wehewehe ʻia e wt.% Cr + 3.3 (wt.% Mo + 0, 5 wt % W) + 16 wt %.N12.ʻO kona kūpaʻa ʻino maikaʻi e hilinaʻi ʻia i ka haku mele ʻana i loaʻa ma kahi o 50% ferritic (α) a me 50% austenitic (γ).Ua hoʻomaikaʻi ʻo HDSS i nā waiwai mechanical a me ke kūpaʻa chlorine kiʻekiʻe ma mua o ka DSS13 maʻamau.Nā hiʻohiʻona o ka ʻino kemika.Hoʻonui ka pale ʻana i ka corrosion i ka hoʻohana ʻana i ka HDSS ma nā wahi chloride koʻikoʻi e like me nā kaiapuni moana.
He pilikia koʻikoʻi ka MIC ma nā ʻoihana he nui, e like me ka aila a me ke kinoea a me ka lako wai14.ʻO MIC ka 20% o nā pōʻino ʻino a pau15.ʻO ka MIC kahi pōʻino bioelectrochemical hiki ke ʻike ʻia ma nā kaiapuni he nui16.ʻO ka hoʻokumu ʻana o nā biofilms ma nā ʻili metala e hoʻololi i nā kūlana electrochemical a pēlā e hoʻololi ai i ke kaʻina hana ʻino.Ua ʻae ʻia ʻo ka MIC corrosion ke kumu e biofilms14.ʻAi nā microorganism electrogenic i nā metala i mea e loaʻa ai ka ikehu no ke ola ʻana17.Ua hōʻike ʻia nā haʻawina MIC hou ʻo EET (extracellular electron transfer) ka mea palena no ka MIC i hoʻokomo ʻia e nā microorganism electrogenic.Ua hōʻike ʻo Zhang et al.18 i ka hoʻololi ʻana o ka electron mediators ma waena o nā pūnaewele sessile Desulfovibrio vulgaris a me 304 stainless steel, e hopena i ka hoʻouka kaua MIC.ʻO Anning et al.19 a me Wenzlaff et al.20 ua hōʻike i nā biofilms o corrosive sulfate-reducing bacteria (SRBs) hiki ke hoʻopaʻa pololei i nā electrons mai nā substrate metala, e hopena i ka lua nui.
ʻIke ʻia ʻo DSS e hiki ke maʻalahi i ka MIC i loko o ka media i loaʻa nā SRBs, iron-reducing bacteria (IRBs), etc. 21.Hoʻokumu kēia mau huakini i ka lua kūloko ma ka ʻili o ka DSS ma lalo o ka biofilm22,23.ʻAʻole like me DSS, ʻike liʻiliʻi e pili ana i ka MIC HDSS24.
ʻO ka Pseudomonas aeruginosa he mea kino Gram-negative, motile, ʻano koʻokoʻo i laha nui ʻia ma ke ʻano25.ʻO Pseudomonas aeruginosa ka microbiota nui ke kuleana no ka MIC o ke kila ma ke kai moana26.Hoʻopili pololei ʻia nā ʻano Pseudomonas i nā kaʻina hana corrosion a ua ʻike ʻia ʻo ia ka poʻe colonizer mua i ka wā biofilm formation27.Mahat et al.28 a ʻo Yuan et al.Ua hōʻike ʻo 29 i ka Pseudomonas aeruginosa e hoʻonui i ka nui o ka corrosion o nā kila māmā a me nā mea hoʻohui i nā kaiaola.
ʻO ka pahuhopu nui o kēia hana ʻo ia ke aʻo ʻana i nā waiwai MIC o 2707 HDSS i hoʻokumu ʻia e ka marine aerobic bacterium Pseudomonas aeruginosa me ka hoʻohana ʻana i nā ʻano electrochemical, nā ʻano loiloi ʻili a me ka nānā ʻana i nā huahana corrosion.Ua hana ʻia nā haʻawina electrochemical e pili ana i ka open circuit potential (OCP), linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS) a me dynamic potential polarization e aʻo i ke ʻano o ka MIC 2707 HDSS.Hana ʻia ka nānā ʻana o ka ikehu dispersive spectroscopy (EDS) no ka ʻike ʻana i nā mea kemika ma nā ʻaoʻao i ʻino.Eia kekahi, ua hoʻoholo ʻia ka paʻa o ka passivation kiʻiʻoniʻoni oxide ma lalo o ka mana o kahi kaiapuni moana i loaʻa iā Pseudomonas aeruginosa e X-ray photoelectron spectroscopy (XPS).Ua ana ʻia ka hohonu o nā lua ma lalo o kahi confocal laser scanning microscope (CLSM).
Hōʻike ka Papa 1 i ka haku mele ʻana o 2707 HDSS.Hōʻike ka Papa 2 i ka 2707 HDSS i nā waiwai mechanical maikaʻi loa me ka ikaika o 650 MPa.Ma ka fig.Hōʻike ka 1 i ka microstructure optical o ka wela wela i mālama ʻia 2707 HDSS.Hiki ke ʻike ʻia nā pūʻulu lōʻihi o austenitic a me nā pae ferritic me ka ʻole o nā pae lua ma kahi microstructure i loaʻa ma kahi o 50% austenitic a me 50% ferritic phases.
Ma ka fig.Hōʻike ka 2a i ka hiki ke kaapuni hāmama (Eocp) me ka manawa hōʻike no 2707 HDSS ma 2216E abiotic medium a me Pseudomonas aeruginosa broth no 14 mau lā ma 37°C.Ua ʻike ʻia ʻo nā loli nui loa i Eocp i loaʻa i nā hola 24 mua.Ua piʻi nā waiwai Eocp ma nā hihia ʻelua ma kahi o -145 mV (versus SCE) ma kahi o 16 mau hola a laila hāʻule nui i -477 mV (versus SCE) a me -236 mV (versus SCE) no nā laʻana non-biological a me P no ka pili. SCE) lau patina.Ma hope o 24 hola, ka Eocp waiwai o Pseudomonas aeruginosa 2707 HDSS i noho paʻa ma -228 mV (hoʻohālikelike ʻia me SCE), ʻoiai ka waiwai kūpono no ka hāpana non-biological ma kahi o -442 mV (hoʻohālikelike ʻia me SCE).Eocp ma ke alo o Pseudomonas aeruginosa he haʻahaʻa loa.
ʻO ka hoʻāʻo electrochemical o 2707 HDSS laʻana i loko o ka media abiotic a me ka broth Pseudomonas aeruginosa ma 37°C:
(a) Hoʻololi i ka Eocp me ka manawa hoʻolaha, (b) ka pihi polarization i ka lā 14, (c) hoʻololi i ka Rp me ka manawa hoʻolaha, (d) hoʻololi i ka corr me ka manawa hoʻolaha.
Hōʻike ka papa 3 i nā ʻāpana electrochemical corrosion o 2707 HDSS samples i hōʻike ʻia i ka abiotic a me ka P. aeruginosa inoculated media ma kahi o 14 mau lā.ʻO Tangential extrapolation o nā anodic a me cathodic curves i ka intersection point i hiki ke hoʻoholo i ka corrosion current density (icorr), corrosion potential (Ecorr) a me Tafel slope (βα a me βc) e like me nā kumu maʻamau30,31.
E like me ka mea i hōʻike ʻia ma ke Kiʻi 2b, ʻo ka neʻe ʻana i luna o ka P. aeruginosa curve i hoʻonui i ka Ecorr i hoʻohālikelike ʻia me ka curve abiotic.ʻO ka waiwai icorr o ka hāpana i loaʻa iā Pseudomonas aeruginosa, e like me ka nui o ka corrosion, ua hoʻonui ʻia i 0.328 µA cm-2, ʻo ia ka ʻehā mau manawa ʻoi aku ka nui o ka hāpana non-biological (0.087 µA cm-2).
ʻO ka LPR kahi ʻano electrochemical maʻamau no ka nānā ʻana i ka ʻino ʻole.Ua hoʻohana ʻia e aʻo i ka MIC32.Ma ka fig.Hōʻike ʻo 2c i ka hoʻololi ʻana i ke kūpaʻa polarization (Rp) ma muli o ka manawa hōʻike.ʻO ke kumu kūʻai Rp kiʻekiʻe, ʻo ia ka liʻiliʻi o ka corrosion.I loko o nā hola 24 mua, ua piʻi ka Rp 2707 HDSS i ka 1955 kΩ cm2 no nā mea olaola ʻole a me 1429 kΩ cm2 no nā specimens Pseudomonas aeruginosa.Hōʻike pū ka Paʻi 2c i ka emi wikiwiki ʻana o ke kumukūʻai Rp ma hope o hoʻokahi lā a laila ʻaʻole i loli iki i nā lā he 13 e hiki mai ana.ʻO ka waiwai Rp no ka Pseudomonas aeruginosa hōʻike hōʻike ma kahi o 40 kΩ cm2, ʻoi aku ka haʻahaʻa ma mua o ka waiwai 450 kΩ cm2 no ka mea hoʻāʻo non-biological.
Ua like ka waiwai o ka icorr i ka helu corrosion like.Hiki ke helu 'ia kona waiwai mai ka hoohalike Stern-Giri:
Wahi a Zoe et al.33 Ua lawe ʻia ka pali Tafel B ma ke ʻano he 26 mV/dec ma kēia hana.Ma ka fig.Hōʻike ka 2d i ka paʻa o ka icorr o ka 2707 abiotic strain, aʻo ka icorr o ka pūʻali Pseudomonas aeruginosa i lele ikaika me ka lele nui ma hope o nā hola 24 mua.ʻO ka waiwai icorr o ka laʻana hoʻāʻo Pseudomonas aeruginosa he kauoha o ka nui i ʻoi aku ka nui ma mua o ka mana non-biological.Kūlike kēia ʻano me nā hopena o ke kū'ē polarization.
ʻO EIS kekahi ʻano hana luku ʻole i hoʻohana ʻia e ʻike i nā hopena electrochemical ma kahi interface corrosion34.Impedance spectra a me ka capacitance helu ana o na strips i hoikeia i ka abiotic media a me na solutions o Pseudomonas aeruginosa, Rb ke ku'e o ka passive/biofilm i hookumuia ma ka ili o ke kaula, Rct ka uku hoololi ku'e, Cdl ka uila papalua.) a me QCPE mau ʻāpana ʻāpana (CPE).Hoʻopili hou ʻia kēia mau ʻāpana ma ka hoʻohālikelike ʻana i ka ʻikepili me kahi ʻano hoʻohālike uila like (EEC).
Ma ka fig.Hōʻike ʻo 3 i nā ʻāpana Nyquist maʻamau (a a me b) a me nā ʻāpana Bode (a' a me b') o 2707 HDSS nā laʻana i loko o ka media abiotic a me ka broth Pseudomonas aeruginosa i nā manawa incubation.Ma ke alo o Pseudomonas aeruginosa, emi ke anawaena o ka loop Nyquist.Hōʻike ka ʻāpana Bode (Fig. 3b ') i ka piʻi ʻana o ka impedance holoʻokoʻa.Hiki ke loaʻa ka ʻike e pili ana i ka manawa hoʻomaha mau mai ka pae maxima.Ma ka fig.Hōʻike ka 4 i nā hale kino a me ka EEC pili i hoʻokumu ʻia ma kahi papa hoʻokahi (a) a me ʻelua-papa (b).Hoʻokomo ʻia ʻo CPE i ke ʻano hoʻohālike EEC.Hōʻike ʻia kona ʻae a me ka impedance penei:
ʻElua mau hiʻohiʻona kino a me nā kaapuni like like no ka hoʻopili ʻana i ka 2707 HDSS coupon impedance spectrum:
ʻO ka Y0 ka nui o ka CPE, ʻo j ka helu noʻonoʻo a i ʻole (−1) 1/2, ʻo ω ke alapine angular, a ʻo n ka mea mana CPE ma lalo o hoʻokahi35.ʻO ka hoʻohuli ʻana i ke kūʻē ʻana o ka hoʻoili kālā (ʻo ia hoʻi, 1/Rct) pili i ka nui o ka corrosion.ʻO ka waiwai Rct haʻahaʻa, ʻo ia hoʻi, ʻoi aku ka nui o ka corrosion rate27.Ma hope o 14 mau lā o ka incubation, hiki i ka Rct o ka hāpana ho'āʻo o Pseudomonas aeruginosa i 32 kΩ cm2, ʻoi aku ka liʻiliʻi ma mua o ka 489 kΩ cm2 o ka hāpana hoʻāʻo non-biological (Table 4).
Nā kiʻi CLSM a me nā kiʻi SEM ma fig.Hōʻike maopopo ʻia ka uhi ʻana o ka biofilm ma ka ʻili o ka laʻana HDSS 2707 ma hope o 7 mau lā.Eia nō naʻe, ma hope o 14 mau lā ua liʻiliʻi ka uhi ʻana o ka biofilm a ua ʻike ʻia kekahi mau mea make.Hōʻike ka papa 5 i ka mānoanoa biofilm o 2707 HDSS laʻana ma hope o 7 a me 14 mau lā o ka ʻike ʻana iā Pseudomonas aeruginosa.Ua hoʻololi ʻia ka mānoanoa biofilm kiʻekiʻe mai 23.4 µm ma hope o 7 mau lā a i 18.9 µm ma hope o 14 mau lā.Ua hōʻoia pū ka mānoanoa biofilm maʻamau i kēia ʻano.Ua emi mai ka 22.2 ± 0.7 μm ma hope o 7 mau lā i 17.8 ± 1.0 μm ma hope o 14 lā.
(a) 3-D CLSM kiʻi ma 7 lā, (b) 3-D CLSM kiʻi ma 14 lā, (c) SEM kiʻi ma 7 lā, a (d) SEM kiʻi ma 14 lā.
Ua hōʻike ʻo EMF i nā mea kemika i ka biofilm a me nā huahana corrosion ma nā laʻana i hōʻike ʻia iā Pseudomonas aeruginosa no 14 mau lā.Ma ka fig.Hōʻike ka Figure 6 ʻoi aku ka kiʻekiʻe o ka mea o C, N, O, P i loko o ka biofilm a me nā huahana corrosion ma mua o ka metala maʻemaʻe, no ka mea, pili kēia mau mea me ka biofilm a me kāna mau metabolites.Pono nā microorganism i ka nui o ka Cr a me Fe.ʻO ka maʻiʻo kiʻekiʻe o Cr a me Fe i loko o ka biofilm a me nā huahana corrosion ma ka ʻili o ka hāpana e hōʻike ana i ka nalowale o nā mea i loko o ka matrix metala ma muli o ka corrosion.
Ma hope o 14 mau lā, ua ʻike ʻia nā lua me ka P. aeruginosa ma waena o 2216E.Ma mua o ka hoʻouluʻana, ua maʻalahi kaʻili o nā mea hoʻohālike a me nā hemahema (Fig. 7a).Ma hope o ka hoʻoulu ʻana a me ka wehe ʻana i nā huahana biofilm a me ka corrosion, ua nānā ʻia nā lua hohonu loa ma ka ʻili o ka hāpana me ka hoʻohana ʻana i ka CLSM, e like me ka hōʻike ʻana ma ka Fig. 7b a me c.ʻAʻohe lua i ʻike ʻia ma ka ʻili o ka mana non-biological (ka hohonu lua 0.02 µm).ʻO ka hohonu o ka lua nui i hoʻokumu ʻia e Pseudomonas aeruginosa he 0.52 µm ma hope o 7 mau lā a me 0.69 µm ma hope o 14 mau lā, ma muli o ka awelika o ka hohonu o ka lua mai 3 mau mea hoʻohālike (ua koho ʻia nā hohonu lua he 10 no kēlā me kēia hāpana) a hiki i ka 0. 42 ± 0.12 µm. .a me 0.52 ± 0.15 µm (Pau 5).He liʻiliʻi kēia mau waiwai hohonu dimple akā koʻikoʻi.
(a) ma mua o ka hoʻolaha ʻana;(b) 14 lā i loko o kahi kaiapuni abiotic;(c) 14 mau lā i ka broth P. aeruginosa.
Ma ka fig.Hōʻike ka Papa 8 i ke kikoʻī XPS o nā ʻāpana hoʻohālike like ʻole, a ua hōʻuluʻulu ʻia ka kemika i kālailai ʻia no kēlā me kēia ʻili ma ka Papa 6. Ma ka Papa 6, ua emi loa nā pākēneka atomika o Fe a me Cr i mua o ka P. aeruginosa (nā laʻana A a me B. ) ma mua o nā ʻāpana hoʻomalu non-biological.(nā laʻana C a me D).No kahi laʻana o Pseudomonas aeruginosa, ua hoʻokomo ʻia ka Cr 2p core level spectral curve i nā ʻāpana kiʻekiʻe ʻehā me nā ikaika paʻa (BE) o 574.4, 576.6, 578.3 a me 586.8 eV, i hāʻawi ʻia iā Cr, Cr2O3, CrOHO3 a me Cr( 3, kēlā me kēia (Fig. 9a a me b).No nā laʻana nonbiological, ka spectra o ka pae kumu Cr 2p ma Fig.9c a me d nā piko nui ʻelua o Cr (BE 573.80 eV) a me Cr2O3 (BE 575.90 eV), pakahi.ʻO ka ʻokoʻa ʻoi loa ma waena o ka coupon abiotic a me ka coupon P. aeruginosa ʻo ia ka noho ʻana o Cr6+ a me kahi hapa kiʻekiʻe o Cr(OH)3 (BE 586.8 eV) ma lalo o ka biofilm.
ʻO ka laulā XPS spectra o 2707 HDSS laʻana i loko o ʻelua pāpaʻi no 7 a me 14 mau lā.
(a) 7 lā ka P. aeruginosa hōʻike, (b) 14 lā P. aeruginosa hōʻike, (c) 7 lā abiotic, (d) 14 lā abiotic.
Hōʻike ka HDSS i kahi kiʻekiʻe o ka pale ʻana i ka corrosion i ka hapa nui o nā kaiapuni.Ua hōʻike ʻo Kim et al.2 ua ʻike ʻia ʻo HDSS UNS S32707 he DSS doped loa me PREN ʻoi aku ka nui ma mua o 45. ʻO ka waiwai PREN o HDSS sample 2707 i kēia hana ʻo 49. ʻO kēia ma muli o ka nui o ka Cr content a me nā kiʻekiʻe kiʻekiʻe o Mo a ʻO Ni, he mea pono i nā kaiapuni ʻakika a me nā kaiapuni me ka nui o nā chlorides.Eia kekahi, ʻo ka hoʻohui maikaʻi ʻana a me ka microstructure kīnā ʻole e hāʻawi i ke kūpaʻa a me ka pale ʻana i ka corrosion.ʻOiai ke kūpaʻa maikaʻi ʻana o ka kemika, hōʻike ka ʻikepili hoʻokolohua ma kēia hana ʻaʻole pale loa ʻo 2707 HDSS i nā MIC biofilm Pseudomonas aeruginosa.
Hōʻike nā hopena electrochemical i ka nui o ka corrosion o 2707 HDSS i ka broth Pseudomonas aeruginosa i hoʻonui nui ʻia ma hope o nā lā 14 i hoʻohālikelike ʻia me ka ʻole o ke ola kino.Ma ke Kiʻi 2a, ua ʻike ʻia ka emi ʻana o ka Eocp ma ka abiotic a me ka broth P. aeruginosa i nā hola 24 mua.Ma hope o kēlā, hoʻopau ka biofilm i ka uhi ʻana i ka ʻili o ka hāpana a lilo ʻo Eocp i mea paʻa.Eia naʻe, ʻoi aku ka kiʻekiʻe o ka pae Eocp biotic ma mua o ka pae Eocp abiotic.Aia nā kumu e manaʻoʻiʻo ai ua pili kēia ʻokoʻa me ka hoʻokumu ʻana o nā biofilms P. aeruginosa.Ma ka fig.2g, ʻo ka waiwai icorr o 2707 HDSS i hōʻea i 0.627 µA cm-2 i mua o Pseudomonas aeruginosa, kahi kauoha o ka nui ma mua o ka mana non-biological (0.063 µA cm-2), i kūlike me ka Rct waiwai i ana ʻia e EIS.I loko o nā lā mua, ua hoʻonui ʻia nā waiwai impedance i ka broth P. aeruginosa ma muli o ka hoʻopili ʻana o nā pūnaewele P. aeruginosa a me ka hoʻokumu ʻana o ka biofilm.Eia naʻe, emi ka impedance i ka uhi piha ʻana o ka biofilm i ka ʻili hoʻohālike.Hoʻouka mua ʻia ka papa pale ma muli o ka hoʻokumu ʻana o nā biofilm a me nā metabolites biofilm.No laila, e emi ana ka pale ʻana i ka corrosion i ka manawa, a ʻo ka waiho ʻana o Pseudomonas aeruginosa ke kumu o ka corrosion localized.ʻOkoʻa nā ʻano o nā kaiapuni abiotic.ʻOi aku ka kiʻekiʻe o ke kūpaʻa ʻino o ka mana non-biological ma mua o ka waiwai kūpono o nā laʻana i hōʻike ʻia i ka broth Pseudomonas aeruginosa.Eia kekahi, no nā laʻana abiotic, ua hōʻea ka waiwai Rct 2707 HDSS i 489 kΩ cm2 i ka lā 14, ʻo ia ka 15 mau manawa kiʻekiʻe ma mua o ke alo o Pseudomonas aeruginosa (32 kΩ cm2).No laila, ʻo 2707 HDSS he kūpaʻa maikaʻi loa i ka corrosion i loko o kahi kaona sterile, akā ʻaʻole pale ʻia mai ka hoʻouka ʻana o MIC e Pseudomonas aeruginosa biofilm.
Hiki ke ʻike ʻia kēia mau hopena mai nā pihi polarization ma Fig.2b.Hoʻopili ʻia ka lālā anodic me ka hoʻokumu ʻana o ka biofilm Pseudomonas aeruginosa a me nā hopena oxidation metala.I ka manawa like, ʻo ka hopena cathodic ka emi ʻana o ka oxygen.ʻO ka loaʻa ʻana o P. aeruginosa i hoʻonui nui i ka nui o ka corrosion o kēia manawa, kahi e pili ana i kahi kauoha o ka nui ma mua o ka mana abiotic.Ua hōʻike kēia i ka Pseudomonas aeruginosa biofilm i hoʻonui i ka corrosion localized o 2707 HDSS.Ua ʻike ʻo Yuan et al.29 ua hoʻonui ʻia ka nui o ka corrosion o kahi 70/30 Cu-Ni alloy e Pseudomonas aeruginosa biofilm.Ma muli paha o ka biocatalysis o ka ho'ēmi oxygen e Pseudomonas aeruginosa biofilm.Hiki i kēia ʻike ke wehewehe i ka MIC 2707 HDSS i kēia hana.Hiki i nā biofilm aerobic ke hoʻemi i ka ʻike o ka oxygen ma lalo o lākou.No laila, ʻo ka hōʻole ʻana i ka hoʻihoʻi ʻana i ka ʻili metala me ka oxygen he mea ia e hoʻopili ai i ka MIC i kēia hana.
ʻO Dickinson et al.Manaʻo ʻo 38 e pili pono ana ka nui o nā hopena kemika a me ka electrochemical i ka hana metabolic o ka bacteria i hoʻopili ʻia i ka ʻili hoʻohālike a me ke ʻano o nā huahana corrosion.E like me ka mea i hōʻike ʻia ma ka Figure 5 a me ka Papa 5, ua emi ka helu o nā cell a me ka mānoanoa biofilm ma hope o 14 mau lā.Hiki ke wehewehe ʻia kēia ma ka ʻoiaʻiʻo ma hope o nā lā he 14 ua make ka hapa nui o nā mea heleuma ma ka ili 2707 HDSS ma muli o ka pau ʻana o ka meaʻai ma ka 2216E a i ʻole ka hoʻokuʻu ʻana i nā ion metala ʻona mai ka 2707 HDSS matrix.He palena kēia o nā hoʻokolohua pūʻulu.
Ma kēia hana, hoʻolaha kahi biofilm Pseudomonas aeruginosa i ka hoʻopau kūloko o Cr a me Fe ma lalo o ka biofilm ma ka ʻili o 2707 HDSS (Fig. 6).Ma ka Papa 6, ua emi iho ka Fe a me Cr i ka laana D i ka hoohalike ana me ka laana C, e hoike ana ua malamaia ka hoopau ana o Fe a me Cr e ka P. aeruginosa biofilm ma hope o na la 7 mua.Hoʻohana ʻia ke kaiapuni 2216E e hoʻohālikelike i ke kaiapuni kai.Loaʻa iā ia ka 17700 ppm Cl-, kahi i hoʻohālikelike ʻia me kona ʻike i loko o ka wai kai maoli.ʻO ka loaʻa ʻana o 17700 ppm Cl- ke kumu nui o ka emi ʻana o Cr i nā lā 7 a me 14 mau lā non-biological sample i kālailai ʻia e XPS.Hoʻohālikelike ʻia i ka laʻana hoʻāʻo o Pseudomonas aeruginosa, ʻoi aku ka liʻiliʻi o ka hoʻoheheʻe ʻana o Cr i ka hāpana hoʻāʻo abiotic ma muli o ke kūpaʻa ikaika o 2707 HDSS i ka chlorine i loko o ke kaiapuni abiotic.Ma ka fig.Hōʻike ka 9 i ka hele ʻana o Cr6+ i ke kiʻiʻoniʻoni passivating.Pili paha kēia i ka wehe ʻana o Cr mai nā ʻili kila e nā biofilms P. aeruginosa, e like me ka manaʻo o Chen a me Clayton39.
Ma muli o ka ulu ʻana o ka maʻi bacteria, ʻo ka pH o ka waena ma mua a ma hope o ka incubation he 7.4 a me 8.2.No laila, ʻaʻole hiki i ka corrosion o nā waikawa organik ke kōkua i kēia hana ma lalo o nā biofilms P. aeruginosa ma muli o ke kiʻekiʻe o ka pH i loko o ka mea nui.ʻAʻole i loli nui ka pH o ka mea hoʻokele non-biological control (mai ka 7.4 mua a i ka 7.5 hope) i ka wā hoʻāʻo 14 lā.ʻO ka piʻi ʻana o ka pH i loko o ka inculum medium ma hope o ka incubation ua pili pū me ka hana metabolic o Pseudomonas aeruginosa, a ua ʻike ʻia ka hopena like ma ka pH i ka loaʻa ʻole o ka pahu hoʻāʻo.
E like me ka hoike ana ma ka fig.7, ʻo ka hohonu hohonu o ka lua i hoʻokumu ʻia e ka biofilm Pseudomonas aeruginosa he 0.69 µm, ʻoi aku ka nui ma mua o ka mea abiotic (0.02 µm).Ua ʻae kēia me ka ʻikepili electrochemical ma luna.Ma lalo o nā kūlana like, ʻoi aku ka hohonu o ka lua o 0.69 µm ma mua o ʻumi manawa liʻiliʻi ma mua o ka waiwai 9.5 µm i kuhikuhi ʻia no 2205 DSS40.Hōʻike kēia mau ʻikepili e hōʻike ana ʻo 2707 HDSS i ke kūʻē maikaʻi ʻana i nā MIC ma mua o 2205 DSS.ʻAʻole kēia he mea kupanaha mai ka 2707 HDSS he kiʻekiʻe ka Cr kiʻekiʻe, kahi e hiki ai i ka passivation lōʻihi, hana i ka Pseudomonas aeruginosa paʻakikī i ka depassivate, a hoʻomaka i ke kaʻina hana me ka ʻole o ka ua pōʻino lua Pitting41.
I ka hopena, ua ʻike ʻia ka lua MIC ma 2707 HDSS surfaces i loko o ka broth Pseudomonas aeruginosa, ʻoiai ʻaʻole naʻaupō ka lua ʻana i ka media abiotic.Hōʻike kēia hana i ka 2707 HDSS i ʻoi aku ka maikaʻi o ke kūʻē ʻana i ka MIC ma mua o 2205 DSS, akā ʻaʻole ia e pale ʻole i ka MIC ma muli o ka biofilm Pseudomonas aeruginosa.Kōkua kēia mau hopena i ke koho ʻana i nā kila kuhili ʻole kūpono a me ka manaʻolana ola no ke kaiapuni kai.
Hāʻawi ʻia ka 2707 HDSS samples e ke Kula o Metallurgy, Northeastern University (NEU), Shenyang, Kina.Hōʻike ʻia ka haku mele ʻana o 2707 HDSS ma ka Papa 1, i nānā ʻia e ke Keʻena ʻIke Mea Hana a me ka ʻOihana Hoʻāʻo o ke Kulanui o Northeheast.Ua mālama ʻia nā laʻana a pau no ka hoʻonā paʻa ma 1180°C no 1 hola.Ma mua o ka hoʻāʻo ʻana i ka corrosion, 2707 HDSS coin steel me kahi ākea ākea o 1 cm2 i hoʻoliʻi ʻia i 2000 grit me ka silicon carbide sandpaper a laila hoʻomaʻamaʻa hou ʻia me ka 0.05 µm Al2O3 pauka slurry.Mālama ʻia nā ʻaoʻao a me lalo me ka pena inert.Ma hope o ka maloʻo ʻana, holoi ʻia nā laʻana me ka wai deionized sterile a sterilized me 75% (v / v) ethanol no 0.5 h.Hoʻomaloʻo ʻia lākou ma lalo o ke kukui ultraviolet (UV) no 0.5 mau hola ma mua o ka hoʻohana ʻana.
Ua kūʻai ʻia ʻo Marine strain Pseudomonas aeruginosa MCCC 1A00099 mai Xiamen Marine Culture Collection (MCCC), Kina.Ua hoʻohana ʻia ʻo Marine 2216E wai (Qingdao Hope Biotechnology Co., Ltd., Qingdao, Kina) i ka moʻomeheu Pseudomonas aeruginosa i loko o 250 ml flasks a me 500 ml electrochemical glass cell ma lalo o nā kūlana aerobic ma 37°C.Loaʻa (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 SrBr2, 0.08 SrBr2, 0.08 SrBr2, 0.08 SrBr2 0.008, 0.008 Na4F0H20PO.1.0 mea hū a me 0.1 hao citrate.ʻO Autoclave ma 121 ° C no 20 min ma mua o ka inoculation.Ua helu ʻia nā cell sessile a me planktonic ma lalo o kahi microscope māmā me ka hoʻohana ʻana i kahi hemocytometer ma 400x kiʻekiʻe.ʻO ka neʻe mua ʻana o nā cell planktonic P. aeruginosa ma hope koke o ka inoculation ma kahi o 106 cell/mL.
Ua lawe ʻia nā hoʻāʻo electrochemical i loko o kahi keʻena aniani ʻekolu-electrode maʻamau me ka nui o 500 ml.Ua hoʻopili ʻia kahi pepa platinum a me kahi electrode calomel saturated (SCE) i ka reactor ma o kahi capillary Luggin i hoʻopiha ʻia me kahi alahaka paʻakai a lawelawe ʻia ma ke ʻano he counter a me nā electrodes kuhikuhi, kēlā me kēia.No ka hana ʻana i ka electrode hana, ua hoʻopili ʻia ke kaula keleawe i hoʻopaʻa ʻia i ka lāʻau i kēlā me kēia laʻana a uhi ʻia me ka epoxy, e waiho ana ma kahi o 1 cm2 o ka ʻili ma kekahi ʻaoʻao no ka electrode hana.I ka wā o nā ana electrochemical, ua waiho ʻia nā laʻana i loko o ka medium 2216E a mālama ʻia i kahi mahana incubation mau (37 ° C) i loko o kahi ʻauʻau wai.ʻO OCP, LPR, EIS a me nā ʻikepili polarization hiki ke ana ʻia me ka hoʻohana ʻana i kahi Autolab potentiostat (Reference 600TM, Gamry Instruments, Inc., USA).Ua hoʻopaʻa ʻia nā hoʻāʻo LPR ma kahi helu scan o 0.125 mV s-1 ma ka -5 a me 5 mV ākea a me Eocp me kahi helu hoʻohālike o 1 Hz.Ua hana ʻia ʻo EIS ma kahi kūlana paʻa Eocp me ka hoʻohana ʻana i ka volta i hoʻohana ʻia o 5 mV me kahi sinusoid ma luna o kahi alapine o 0.01 a 10,000 Hz.Ma mua o ka hiki ke kahili, aia nā electrodes ma ke ʻano kaapuni hāmama a hiki i ka hiki ʻana o ka hiki ke hoʻopaʻa ʻia o 42.Me.Ua hana hou ʻia kēlā me kēia hoʻokolohua me ka Pseudomonas aeruginosa a me ka ʻole.
ʻO nā laʻana no ka nānā ʻana i ka metallographic i hoʻomaʻamaʻa ʻia me ka 2000 grit wet SiC pepa a laila hoʻomaloʻo ʻia me kahi slurry pauka 0.05 µm Al2O3 no ka nānā ʻana.Hoʻohana ʻia ka ʻike metallographic me ka microscope optical.Ua kaha ʻia ka hāpana me ka solution 10 wt% potassium hydroxide43.
Ma hope o ka incubation, holoi 3 manawa me ka phosphate buffered saline (PBS) (pH 7.4 ± 0.2) a laila hoʻoponopono me 2.5% (v/v) glutaraldehyde no 10 mau hola e hoʻoponopono ai i ka biofilm.ʻO ka hoʻomaloʻo ʻana me ka ethanol ma kahi moʻo stepped (50%, 60%, 70%, 80%, 90%, 95% a me 100% ma ka leo) ma mua o ka maloʻo ʻana o ka ea.ʻO ka hope, ua hoʻolele ʻia kahi kiʻi gula ma ka ʻili o ka hāpana e hāʻawi i ka conductivity no ka nānā ʻana iā SEM44.Hoʻopili ʻia nā kiʻi SEM ma ka wahi me nā pūnana P. aeruginosa i hoʻokumu ʻia ma ka ʻili o kēlā me kēia hāpana.Ua hana ʻia ka loiloi EMF e ʻike i nā mea kemika.No ke ana ʻana i ka hohonu o ka lua, ua hoʻohana ʻia kahi Zeiss confocal laser scanning microscope (CLSM) (LSM 710, Zeiss, Kelemānia).No ka nānā ʻana i nā lua ʻino ma lalo o ka biofilm, ua hoʻomaʻemaʻe mua ʻia ka laʻana hoʻāʻo e like me ka Chinese National Standard (CNS) GB/T4334.4-2000 e wehe i nā huahana corrosion a me biofilm mai ka ʻili o ka hāpana hoʻāʻo.
X-ray photoelectron spectroscopy (XPS, ESCALAB250 Surface Analysis System, Thermo VG, USA) ka hoʻohana ʻana i kahi kumu X-ray monochromatic (laina Al Kα me ka ikehu o 1500 eV a me ka mana o 150 W) ma kahi ākea o nā ikehu hoʻopaʻa. 0 ma lalo o nā kūlana maʻamau o –1350 eV.E hoʻopaʻa i ka spectra hoʻonā kiʻekiʻe e hoʻohana ana i ka ikehu pass 50 eV a me ka nui o ka ʻanuʻu 0.2 eV.
Wehe i ka laʻana i hoʻomoʻa ʻia a holoi mālie me ka PBS (pH 7.4 ± 0.2) no 15 s45.No ka nānā ʻana i ka hiki ʻana o ka maʻi bacteria o ka biofilm ma ka laʻana, ua hoʻopaʻa ʻia ka biofilm me ka hoʻohana ʻana i ka LIVE / DEAD BacLight Bacterial Viability Kit (Invitrogen, Eugene, OR, USA).Aia i loko o ka pahu nā mea hoʻonanea ʻelua: SYTO-9 ʻulaʻula ʻulaʻula a me propidium iodide (PI).Ma CLSM, hōʻike nā kiko ʻōmaʻomaʻo a me ka ʻulaʻula i nā mea ola a me nā mea make.No ka hoʻopaʻa ʻana, e hoʻokomo i 1 ml o ka hui ʻana me 3 µl o SYTO-9 a me 3 µl o ka solution PI ma ka lumi wela (23°C) i ka pōʻeleʻele no 20 mau minuke.Ma hope o kēlā, ua ʻike ʻia nā laʻana stained ma ʻelua mau nalu (488 nm no nā cell ola a me 559 nm no nā cell make) me ka hoʻohana ʻana i kahi mea hana Nikon CLSM (C2 Plus, Nikon, Iapana).E ana i ka mānoanoa biofilm ma ke ʻano hiʻohiʻona 3-D.
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