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Kev loj hlob sai ntawm nanotechnology thiab nws txoj kev koom ua ke rau hauv kev siv txhua hnub tuaj yeem ua rau ib puag ncig muaj kev phom sij. Txawm hais tias cov txheej txheem ntsuab rau kev rhuav tshem cov organic contaminations tau tsim zoo, kev rov qab los ntawm cov inorganic crystalline contaminations yog qhov txhawj xeeb loj vim lawv tsis tshua muaj kev cuam tshuam rau biotransformation thiab tsis nkag siab txog kev sib cuam tshuam ntawm cov khoom siv nrog cov khoom siv biological. Ntawm no, peb siv Nb-based inorganic 2D MXenes qauv ua ke nrog txoj kev tshuaj xyuas cov duab yooj yim los taug qab cov txheej txheem bioremediation ntawm 2D ceramic nanomaterials los ntawm cov microalgae ntsuab Raphidocelis subcapitata. Peb pom tias microalgae rhuav tshem Nb-based MXenes vim muaj kev sib cuam tshuam physico-chemical cuam tshuam nrog nto. Thaum xub thawj, ib txheej thiab ntau txheej MXene nanoflakes tau txuas rau ntawm qhov chaw ntawm microalgae, uas txo qis kev loj hlob ntawm algae. Txawm li cas los xij, thaum muaj kev sib cuam tshuam ntev nrog qhov chaw, microalgae oxidized MXene nanoflakes thiab ntxiv decomposed lawv mus rau hauv NbO thiab Nb2O5. Vim tias cov oxides no tsis muaj tshuaj lom rau cov hlwb microalgae, lawv noj Nb oxide nanoparticles los ntawm lub tshuab nqus dej uas rov qab kho cov microalgae tom qab 72 teev ntawm kev kho dej. Cov teebmeem ntawm cov as-ham cuam tshuam nrog kev nqus kuj pom tseeb hauv kev nce hauv qhov ntim ntawm lub hlwb, lawv cov duab du thiab kev hloov pauv ntawm kev loj hlob. Raws li cov kev tshawb pom no, peb xaus lus tias qhov muaj Nb-based MXenes luv luv thiab ntev hauv cov ecosystem dej qab zib yuav ua rau muaj kev cuam tshuam me me rau ib puag ncig. Nws yog qhov tsim nyog tias, siv ob-seem nanomaterials ua cov qauv qauv, peb qhia txog qhov ua tau ntawm kev taug qab kev hloov pauv duab txawm tias nyob rau hauv cov ntaub ntawv zoo. Zuag qhia tag nrho, kev tshawb fawb no teb cov lus nug tseem ceeb txog cov txheej txheem cuam tshuam nrog kev sib cuam tshuam ntawm qhov chaw tsav tsheb lub tshuab bioremediation ntawm 2D nanomaterials thiab muab lub hauv paus rau kev tshawb fawb luv luv thiab ntev ntawm kev cuam tshuam rau ib puag ncig ntawm cov inorganic crystalline nanomaterials.
Txij li thaum lawv tshawb pom cov khoom siv nano, cov khoom siv nanotechnologies tau tsim ntau yam kev txaus siab, thiab ntau yam nanotechnologies tau nkag mus rau theem niaj hnub1. Hmoov tsis zoo, kev koom ua ke ntawm cov khoom siv nano rau hauv cov ntawv thov txhua hnub tuaj yeem ua rau muaj kev tso tawm tsis raug vim yog kev pov tseg tsis raug, kev tuav tsis zoo, lossis kev nyab xeeb tsis txaus. Yog li ntawd, nws yog qhov tsim nyog los xav tias cov khoom siv nano, suav nrog ob-seem (2D) nanomaterials, tuaj yeem tso tawm rau hauv ib puag ncig ntuj, tus cwj pwm thiab kev ua ub no ntawm cov tsiaj txhu uas tseem tsis tau nkag siab tag nrho. Yog li ntawd, nws tsis yog qhov xav tsis thoob tias kev txhawj xeeb txog ecotoxicity tau tsom mus rau lub peev xwm ntawm 2D nanomaterials kom leach rau hauv cov kab ke hauv dej2,3,4,5,6. Hauv cov ecosystems no, qee cov khoom siv nano2D tuaj yeem cuam tshuam nrog ntau yam kab mob ntawm ntau theem trophic, suav nrog microalgae.
Cov kab me me (microalgae) yog cov kab mob qub uas pom muaj nyob rau hauv cov dej qab zib thiab cov dej hiav txwv uas tsim ntau yam khoom siv tshuaj lom neeg los ntawm photosynthesis7. Yog li ntawd, lawv tseem ceeb rau cov dej hauv dej8,9,10,11,12 tab sis kuj tseem ceeb, pheej yig thiab siv dav dav cov cim qhia txog kev lom neeg hauv dej13,14. Txij li thaum cov hlwb microalgae loj hlob sai thiab teb sai rau qhov muaj ntau yam tshuaj sib xyaw, lawv cog lus tias yuav tsim cov txheej txheem zoo rau ib puag ncig rau kev kho cov dej uas muaj kuab paug nrog cov khoom siv organic15,16.
Cov hlwb algae tuaj yeem tshem tawm cov inorganic ions ntawm dej los ntawm biosorption thiab accumulation17,18. Qee hom algal xws li Chlorella, Anabaena invar, Westiellopsis prolifica, Stigeoclonium tenue thiab Synechococcus sp. Nws tau pom tias nqa thiab txawm tias pub cov hlau lom ions xws li Fe2 +, Cu2 +, Zn2 + thiab Mn2 + 19. Lwm cov kev tshawb fawb tau qhia tias Cu2 +, Cd2 +, Ni2 +, Zn2 + lossis Pb2 + ions txwv kev loj hlob ntawm Scenedesmus los ntawm kev hloov pauv cell morphology thiab rhuav tshem lawv cov chloroplasts20,21.
Cov txheej txheem ntsuab rau kev rhuav tshem cov pa phem organic thiab tshem tawm cov hlau hnyav ions tau nyiam cov kws tshawb fawb thiab cov engineers thoob ntiaj teb. Qhov no feem ntau yog vim qhov tseeb tias cov pa phem no tau yooj yim ua tiav hauv theem kua. Txawm li cas los xij, cov pa phem inorganic crystalline yog tus cwj pwm los ntawm kev yaj dej tsawg thiab tsis tshua muaj kev cuam tshuam rau ntau yam biotransformations, uas ua rau muaj teeb meem loj hauv kev kho, thiab muaj kev vam meej me ntsis hauv thaj chaw no22,23,24,25,26. Yog li, kev tshawb nrhiav cov kev daws teeb meem zoo rau ib puag ncig rau kev kho cov nanomaterials tseem yog thaj chaw nyuaj thiab tsis tau tshawb nrhiav. Vim muaj qib siab ntawm kev tsis paub meej txog cov teebmeem biotransformation ntawm 2D nanomaterials, tsis muaj txoj hauv kev yooj yim los nrhiav cov txoj hauv kev ua tau ntawm lawv qhov kev puas tsuaj thaum lub sijhawm txo qis.
Hauv kev tshawb fawb no, peb tau siv cov microalgae ntsuab ua tus neeg sawv cev rau cov khoom siv inorganic ceramic, ua ke nrog kev saib xyuas qhov chaw ntawm cov txheej txheem degradation ntawm MXene ua tus sawv cev ntawm cov khoom siv inorganic ceramic. Lo lus "MXene" qhia txog stoichiometry ntawm cov khoom siv Mn + 1XnTx, qhov twg M yog cov hlau hloov pauv thaum ntxov, X yog carbon thiab / lossis nitrogen, Tx yog qhov chaw xaus (piv txwv li, -OH, -F, -Cl), thiab n = 1, 2, 3 lossis 427.28. Txij li thaum Naguib et al. Sensorics, kev kho mob qog noj ntshav thiab kev lim dej membrane 27,29,30. Tsis tas li ntawd, MXenes tuaj yeem suav hais tias yog cov qauv 2D systems vim lawv qhov kev ruaj khov zoo heev thiab kev sib cuam tshuam ntawm cov kab mob 31,32,33,34,35,36.
Yog li ntawd, txoj kev tshawb fawb uas tau tsim tawm hauv tsab xov xwm no thiab peb cov kev tshawb fawb tau pom hauv Daim Duab 1. Raws li qhov kev xav no, microalgae rhuav tshem Nb-based MXenes mus rau hauv cov tshuaj tsis muaj tshuaj lom vim muaj kev sib cuam tshuam ntawm lub cev thiab tshuaj lom neeg, uas ua rau cov algae rov qab zoo dua. Txhawm rau sim qhov kev xav no, ob tug tswv cuab ntawm tsev neeg ntawm cov hlau hloov pauv carbides thiab / lossis nitrides (MXenes) raws li niobium thaum ntxov, uas yog Nb2CTx thiab Nb4C3TX, tau raug xaiv.
Txoj kev tshawb fawb thiab cov pov thawj raws li kev xav rau MXene rov qab los ntawm cov kab mob me me Raphidocelis subcapitata. Thov nco ntsoov tias qhov no tsuas yog ib qho kev sawv cev ntawm cov kev xav raws li pov thawj. Lub pas dej ib puag ncig txawv ntawm cov khoom noj khoom haus siv thiab cov xwm txheej (piv txwv li, lub voj voog diurnal thiab cov kev txwv ntawm cov khoom noj khoom haus tseem ceeb muaj). Tsim nrog BioRender.com.
Yog li ntawd, los ntawm kev siv MXene ua tus qauv system, peb tau qhib lub qhov rooj rau kev kawm txog ntau yam kev cuam tshuam ntawm lub cev uas tsis tuaj yeem pom nrog lwm cov nanomaterials ib txwm muaj. Tshwj xeeb, peb qhia txog qhov ua tau ntawm bioremediation ntawm ob-seem nanomaterials, xws li niobium-based MXenes, los ntawm microalgae Raphidocelis subcapitata. Microalgae muaj peev xwm rhuav tshem Nb-MXenes mus rau hauv cov oxides tsis muaj tshuaj lom NbO thiab Nb2O5, uas kuj muab cov as-ham los ntawm niobium uptake mechanism. Zuag qhia tag nrho, kev tshawb fawb no teb cov lus nug tseem ceeb txog cov txheej txheem cuam tshuam nrog kev sib cuam tshuam ntawm lub cev thiab tshuaj lom neeg uas tswj hwm cov txheej txheem ntawm bioremediation ntawm ob-seem nanomaterials. Tsis tas li ntawd, peb tab tom tsim ib txoj kev yooj yim raws li cov duab-parameter-raws li rau kev taug qab cov kev hloov pauv me me hauv cov duab ntawm 2D nanomaterials. Qhov no txhawb nqa kev tshawb fawb luv luv thiab ntev mus rau ntau yam kev cuam tshuam ib puag ncig ntawm cov khoom siv inorganic crystalline nanomaterials. Yog li, peb txoj kev tshawb fawb ua rau kev nkag siab ntau ntxiv txog kev sib cuam tshuam ntawm cov khoom siv thiab cov khoom siv biological. Peb kuj tseem muab lub hauv paus rau kev tshawb fawb luv luv thiab ntev txog lawv cov kev cuam tshuam rau cov ecosystem dej qab zib, uas tam sim no tuaj yeem txheeb xyuas tau yooj yim.
MXenes sawv cev rau ib chav kawm nthuav ntawm cov ntaub ntawv nrog cov khoom siv lub cev thiab tshuaj lom neeg tshwj xeeb thiab zoo nkauj thiab yog li ntawd muaj ntau yam kev siv tau. Cov khoom no feem ntau nyob ntawm lawv cov stoichiometry thiab chemistry nto. Yog li ntawd, hauv peb txoj kev tshawb fawb, peb tau tshawb nrhiav ob hom Nb-raws li hierarchical ib txheej (SL) MXenes, Nb2CTx thiab Nb4C3TX, vim tias cov teebmeem sib txawv ntawm cov khoom siv nanomaterials no tuaj yeem pom. MXenes yog tsim los ntawm lawv cov ntaub ntawv pib los ntawm kev xaiv etching ntawm cov txheej txheem MAX-thin A-layers. Lub sijhawm MAX yog ib lub ternary ceramic uas muaj cov blocks "bonded" ntawm cov hlau hloov pauv carbides thiab cov txheej nyias ntawm cov ntsiab lus "A" xws li Al, Si, thiab Sn nrog MnAXn-1 stoichiometry. Lub morphology ntawm thawj theem MAX tau pom los ntawm kev luam theej duab electron microscopy (SEM) thiab tau sib xws nrog cov kev tshawb fawb yav dhau los (Saib Cov Ntaub Ntawv Ntxiv, SI, Daim Duab S1). Multilayer (ML) Nb-MXene tau txais tom qab tshem tawm Al txheej nrog 48% HF (hydrofluoric acid). Cov morphology ntawm ML-Nb2CTx thiab ML-Nb4C3TX tau raug tshuaj xyuas los ntawm kev siv lub tshuab hluav taws xob scanning (SEM) (Cov duab S1c thiab S1d feem) thiab ib qho morphology MXene uas muaj txheej txheem tau pom, zoo ib yam li ob-seem nanoflakes hla dhau cov qhov zoo li qhov ntev. Ob qho tib si Nb-MXenes muaj ntau yam zoo sib xws nrog MXene theem yav dhau los synthesized los ntawm acid etching27,38. Tom qab lees paub cov qauv ntawm MXene, peb tau txheej nws los ntawm kev sib xyaw ntawm tetrabutylammonium hydroxide (TBAOH) ua raws li kev ntxuav thiab sonication, tom qab ntawd peb tau txais ib-txheej lossis txheej qis (SL) 2D Nb-MXene nanoflakes.
Peb siv cov tshuab hluav taws xob xa hluav taws xob siab (HRTEM) thiab X-ray diffraction (XRD) los sim qhov ua tau zoo ntawm kev etching thiab ntxiv peeling. Cov txiaj ntsig HRTEM ua tiav siv Inverse Fast Fourier Transform (IFFT) thiab Fast Fourier Transform (FFT) tau pom hauv daim duab 2. Nb-MXene nanoflakes tau taw qhia ntug kom xyuas cov qauv ntawm cov txheej atomic thiab ntsuas qhov deb ntawm interplanar. Cov duab HRTEM ntawm MXene Nb2CTx thiab Nb4C3TX nanoflakes tau qhia lawv cov txheej txheem nyias nyias (saib daim duab 2a1, a2), raws li tau tshaj tawm los ntawm Naguib et al.27 thiab Jastrzębska et al.38. Rau ob lub monolayers Nb2CTx thiab Nb4C3Tx uas nyob ib sab, peb tau txiav txim siab qhov deb ntawm 0.74 thiab 1.54 nm, feem (Figs. 2b1,b2), uas kuj pom zoo nrog peb cov txiaj ntsig yav dhau los38. Qhov no tau lees paub ntxiv los ntawm kev hloov pauv Fourier sai (Daim Duab 2c1, c2) thiab kev hloov pauv Fourier sai (Daim Duab 2d1, d2) uas qhia qhov deb ntawm Nb2CTx thiab Nb4C3Tx monolayers. Daim duab qhia txog kev hloov pauv ntawm cov kab teeb thiab tsaus uas sib raug rau niobium thiab carbon atoms, uas lees paub qhov xwm txheej ntawm cov txheej txheem ntawm MXenes uas tau kawm. Nws yog ib qho tseem ceeb uas yuav tsum nco ntsoov tias cov spectra X-ray dispersive energy (EDX) tau txais rau Nb2CTx thiab Nb4C3Tx (Daim Duab S2a thiab S2b) tsis qhia txog cov seem ntawm theem MAX thawj, vim tsis muaj Al peak tau pom.
Kev piav qhia txog SL Nb2CTx thiab Nb4C3Tx MXene nanoflakes, suav nrog (a) high resolution electron microscopy (HRTEM) side-view 2D nanoflake imaging thiab sib xws, (b) intensity mode, (c) inverse fast Fourier transform (IFFT), (d) fast Fourier transform (FFT), (e) Nb-MXenes X-ray patterns. Rau SL 2D Nb2CTx, cov lej yog qhia ua (a1, b1, c1, d1, e1). Rau SL 2D Nb4C3Tx, cov lej yog qhia ua (a2, b2, c2, d2, e1).
Kev ntsuas X-ray diffraction ntawm SL Nb2CTx thiab Nb4C3Tx MXenes tau qhia nyob rau hauv daim duab 2e1 thiab e2, raws li. Cov Peaks (002) ntawm 4.31 thiab 4.32 sib raug rau cov txheej MXenes Nb2CTx thiab Nb4C3TX38,39,40,41 uas tau piav qhia ua ntej. Cov txiaj ntsig XRD kuj qhia txog qhov muaj qee cov qauv ML seem thiab MAX theem, tab sis feem ntau yog cov qauv XRD cuam tshuam nrog SL Nb4C3Tx (Daim duab 2e2). Qhov muaj cov khoom me me ntawm MAX theem yuav piav qhia txog qhov muaj zog MAX ncov piv rau cov txheej Nb4C3Tx uas tau teeb tsa tsis raws cai.
Kev tshawb fawb ntxiv tau tsom mus rau cov microalgae ntsuab uas yog hom R. subcapitata. Peb tau xaiv microalgae vim tias lawv yog cov neeg tsim khoom tseem ceeb uas koom nrog hauv cov khoom noj khoom haus loj42. Lawv kuj yog ib qho ntawm cov cim qhia zoo tshaj plaws ntawm kev lom vim muaj peev xwm tshem tawm cov tshuaj lom uas nqa mus rau qib siab dua ntawm cov saw hlau zaub mov43. Tsis tas li ntawd, kev tshawb fawb ntawm R. subcapitata yuav ua rau pom kev lom ntawm SL Nb-MXenes rau cov kab mob me me hauv dej tshiab. Txhawm rau piav qhia qhov no, cov kws tshawb fawb tau xav tias txhua tus kab mob me me muaj kev nkag siab sib txawv rau cov tshuaj lom uas muaj nyob hauv ib puag ncig. Rau feem ntau cov kab mob, cov tshuaj tsawg tsawg tsis cuam tshuam rau lawv txoj kev loj hlob, thaum cov tshuaj ntau dua qhov txwv tsis pub dhau qee qhov tuaj yeem tiv thaiv lawv lossis txawm tias ua rau tuag. Yog li ntawd, rau peb txoj kev tshawb fawb ntawm kev sib cuam tshuam ntawm microalgae thiab MXenes thiab kev rov qab los, peb tau txiav txim siab los sim cov tshuaj lom thiab tsis muaj teeb meem ntawm Nb-MXenes. Txhawm rau ua qhov no, peb tau sim cov concentration ntawm 0 (ua ib qho piv txwv), 0.01, 0.1 thiab 10 mg l-1 MXene thiab ntxiv rau cov microalgae uas muaj cov concentration siab heev ntawm MXene (100 mg l-1 MXene), uas tuaj yeem ua rau hnyav thiab tuag taus. . rau txhua qhov chaw ib puag ncig.
Cov teebmeem ntawm SL Nb-MXenes rau microalgae tau pom hauv Daim Duab 3, qhia ua feem pua ​​ntawm kev txhawb nqa kev loj hlob (+) lossis kev txwv (-) ntsuas rau 0 mg l-1 qauv. Rau kev sib piv, theem Nb-MAX thiab ML Nb-MXenes kuj tau sim thiab cov txiaj ntsig tau pom hauv SI (saib Daim Duab S3). Cov txiaj ntsig tau txais tau lees paub tias SL Nb-MXenes yuav luag tsis muaj tshuaj lom hauv qhov ntau ntawm cov concentration qis los ntawm 0.01 txog 10 mg / l, raws li tau pom hauv Daim Duab 3a, b. Hauv rooj plaub ntawm Nb2CTx, peb pom tsis ntau tshaj 5% ecotoxicity hauv qhov ntau teev tseg.
Kev txhawb nqa (+) lossis kev txwv tsis pub (-) kev loj hlob ntawm microalgae nyob rau hauv qhov muaj SL (a) Nb2CTx thiab (b) Nb4C3TX MXene. 24, 48 thiab 72 teev ntawm MXene-microalgae kev sib cuam tshuam tau raug tshuaj xyuas. Cov ntaub ntawv tseem ceeb (t-test, p < 0.05) tau cim nrog lub hnub qub (*). Cov ntaub ntawv tseem ceeb (t-test, p < 0.05) tau cim nrog lub hnub qub (*). Значимые данные (t-критерий, p < 0,05) отмечены звездочкой (*). Cov ntaub ntawv tseem ceeb (t-test, p < 0.05) muaj lub cim hnub qub (*).重要数据（t 检验，p <0.05）用星号(*) 标记.重要数据（t 检验，p <0.05）用星号(*) 标记. Важные данные (t-test, p < 0,05) отмечены звездочкой (*). Cov ntaub ntawv tseem ceeb (t-test, p < 0.05) muaj lub cim hnub qub (*).Cov xub liab qhia txog kev tshem tawm ntawm kev txhawb nqa inhibitory.
Ntawm qhov tod tes, qhov tsawg ntawm Nb4C3TX tau hloov mus ua me ntsis lom dua, tab sis tsis siab dua 7%. Raws li xav tau, peb tau pom tias MXenes muaj kev lom ntau dua thiab kev tiv thaiv kev loj hlob ntawm microalgae ntawm 100mg L-1. Qhov nthuav yog, tsis muaj ib yam khoom siv tau qhia tib yam thiab lub sijhawm nyob ntawm cov teebmeem atoxic / lom piv rau cov qauv MAX lossis ML (saib SI kom paub meej). Thaum rau theem MAX (saib daim duab S3) kev lom tau txog li 15-25% thiab nce nrog lub sijhawm, qhov rov qab tau pom rau SL Nb2CTx thiab Nb4C3TX MXene. Kev tiv thaiv kev loj hlob ntawm microalgae tau txo qis dhau sijhawm. Nws tau txog li 17% tom qab 24 teev thiab poob qis dua 5% tom qab 72 teev (Daim duab 3a, b, feem).
Qhov tseem ceeb tshaj, rau SL Nb4C3TX, kev txwv tsis pub loj hlob ntawm microalgae tau txog li 27% tom qab 24 teev, tab sis tom qab 72 teev nws txo qis mus txog li 1%. Yog li ntawd, peb tau sau cov txiaj ntsig pom tias yog kev txwv tsis pub rov qab ntawm kev txhawb nqa, thiab cov txiaj ntsig tau muaj zog dua rau SL Nb4C3TX MXene. Kev txhawb nqa ntawm kev loj hlob ntawm microalgae tau sau tseg ua ntej nrog Nb4C3TX (kev sib cuam tshuam ntawm 10 mg L-1 rau 24 teev) piv nrog SL Nb2CTx MXene. Cov txiaj ntsig rov qab inhibition-stimulation kuj tau pom zoo hauv cov kab biomass doubling rate curve (saib daim duab S4 rau cov ntsiab lus). Txog tam sim no, tsuas yog ecotoxicity ntawm Ti3C2TX MXene tau kawm ntau txoj hauv kev sib txawv. Nws tsis yog lom rau zebrafish embryos44 tab sis me ntsis ecotoxic rau microalgae Desmodesmus quadricauda thiab Sorghum saccharatum nroj tsuag45. Lwm cov piv txwv ntawm cov txiaj ntsig tshwj xeeb suav nrog kev lom ntau dua rau cov kab mob qog noj ntshav dua li cov kab mob ib txwm muaj46,47. Nws tuaj yeem xav tias cov xwm txheej xeem yuav cuam tshuam rau qhov kev hloov pauv ntawm kev loj hlob ntawm microalgae uas pom nyob rau hauv qhov muaj Nb-MXenes. Piv txwv li, pH ntawm kwv yees li 8 hauv chloroplast stroma yog qhov zoo tshaj plaws rau kev ua haujlwm zoo ntawm RuBisCO enzyme. Yog li ntawd, pH hloov pauv cuam tshuam tsis zoo rau qhov nrawm ntawm photosynthesis48,49. Txawm li cas los xij, peb tsis tau pom qhov kev hloov pauv tseem ceeb hauv pH thaum lub sijhawm sim (saib SI, Daim Duab S5 rau cov ntsiab lus). Feem ntau, cov kab lis kev cai ntawm microalgae nrog Nb-MXenes me ntsis txo qis pH ntawm cov tshuaj dhau sijhawm. Txawm li cas los xij, qhov kev txo qis no zoo ib yam li kev hloov pauv hauv pH ntawm cov khoom nruab nrab ntshiab. Tsis tas li ntawd, ntau yam kev hloov pauv pom zoo ib yam li qhov ntsuas rau cov kab lis kev cai ntshiab ntawm microalgae (qauv tswj). Yog li, peb xaus lus tias photosynthesis tsis cuam tshuam los ntawm kev hloov pauv hauv pH dhau sijhawm.
Ntxiv mus, cov MXenes uas tau tsim muaj qhov kawg ntawm qhov chaw (hu ua Tx). Cov no feem ntau yog cov pab pawg ua haujlwm -O, -F thiab -OH. Txawm li cas los xij, cov tshuaj lom neeg ntawm qhov chaw muaj feem cuam tshuam ncaj qha rau txoj kev tsim cov tshuaj. Cov pab pawg no paub tias tau faib ua ntu zus thoob plaws qhov chaw, ua rau nws nyuaj rau kwv yees lawv cov nyhuv rau cov khoom ntawm MXene50. Nws tuaj yeem sib cav tias Tx tuaj yeem yog lub zog catalytic rau kev oxidation ntawm niobium los ntawm lub teeb. Cov pab pawg ua haujlwm ntawm qhov chaw muab ntau qhov chaw anchoring rau lawv cov photocatalysts hauv qab los tsim heterojunctions51. Txawm li cas los xij, cov khoom siv loj hlob tsis tau muab cov photocatalyst zoo (cov khoom siv nruab nrab ntxaws ntxaws tuaj yeem pom hauv SI Rooj S6). Tsis tas li ntawd, txhua qhov kev hloov kho ntawm qhov chaw kuj tseem ceeb heev, vim tias cov haujlwm biological ntawm MXenes tuaj yeem hloov pauv vim yog txheej tom qab ua tiav, oxidation, kev hloov kho ntawm cov tshuaj lom neeg ntawm cov organic thiab inorganic compounds52,53,54,55,56 lossis kev tsim kho ntawm qhov chaw38. Yog li ntawd, txhawm rau sim seb niobium oxide puas muaj feem cuam tshuam nrog kev tsis ruaj khov ntawm cov khoom siv hauv nruab nrab, peb tau ua kev tshawb fawb txog lub peev xwm zeta (ζ) hauv cov kab lis kev loj hlob ntawm microalgae thiab dej deionized (rau kev sib piv). Peb cov txiaj ntsig qhia tau tias SL Nb-MXenes ruaj khov heev (saib SI daim duab S6 rau MAX thiab ML cov txiaj ntsig). Lub peev xwm zeta ntawm SL MXenes yog li -10 mV. Hauv rooj plaub ntawm SR Nb2CTx, tus nqi ntawm ζ yog qhov tsis zoo dua li ntawm Nb4C3Tx. Kev hloov pauv ntawm tus nqi ζ no yuav qhia tau tias qhov chaw ntawm MXene nanoflakes uas muaj nqi tsis zoo nqus cov ions uas muaj nqi zoo los ntawm cov kab lis kev cai. Kev ntsuas lub sijhawm ntawm lub peev xwm zeta thiab kev coj ua ntawm Nb-MXenes hauv cov kab lis kev cai (saib Cov Duab S7 thiab S8 hauv SI kom paub meej ntxiv) zoo li txhawb nqa peb qhov kev xav.
Txawm li cas los xij, ob qho Nb-MXene SLs tau qhia txog kev hloov pauv me me los ntawm xoom. Qhov no qhia meej meej lawv qhov kev ruaj khov hauv cov kab lis kev loj hlob ntawm microalgae. Ntxiv rau, peb tau soj ntsuam seb qhov muaj peb cov microalgae ntsuab puas yuav cuam tshuam rau qhov kev ruaj khov ntawm Nb-MXenes hauv cov kab lis kev cai. Cov txiaj ntsig ntawm zeta lub peev xwm thiab kev coj ua ntawm MXenes tom qab kev sib cuam tshuam nrog microalgae hauv cov khoom noj khoom haus thiab kab lis kev cai dhau sijhawm tuaj yeem pom hauv SI (Cov duab S9 thiab S10). Qhov nthuav yog, peb tau pom tias qhov muaj microalgae zoo li ua kom ruaj khov qhov kev sib kis ntawm ob qho MXenes. Hauv qhov xwm txheej ntawm Nb2CTx SL, qhov muaj peev xwm zeta txawm tias me ntsis txo qis dhau sijhawm mus rau ntau tus nqi tsis zoo (-15.8 piv rau -19.1 mV tom qab 72 teev ntawm kev sib xyaw). Qhov muaj peev xwm zeta ntawm SL Nb4C3TX me ntsis nce, tab sis tom qab 72 teev nws tseem qhia txog kev ruaj khov siab dua li nanoflakes yam tsis muaj microalgae (-18.1 vs. -9.1 mV).
Peb kuj pom tias cov conductivity qis dua ntawm Nb-MXene cov tshuaj uas tau incubated nyob rau hauv qhov muaj microalgae, qhia tias muaj cov ions qis dua hauv cov khoom noj khoom haus nruab nrab. Qhov tseem ceeb, qhov tsis ruaj khov ntawm MXenes hauv dej feem ntau yog vim qhov oxidation ntawm qhov chaw57. Yog li ntawd, peb xav tias cov microalgae ntsuab qee yam tau tshem tawm cov oxides uas tsim rau ntawm qhov chaw ntawm Nb-MXene thiab txawm tias tiv thaiv lawv tshwm sim (oxidation ntawm MXene). Qhov no tuaj yeem pom los ntawm kev kawm txog cov hom tshuaj uas microalgae nqus tau.
Txawm hais tias peb cov kev tshawb fawb txog ecotoxicological qhia tau hais tias microalgae muaj peev xwm kov yeej qhov kev lom ntawm Nb-MXenes dhau sijhawm thiab qhov tsis tshua muaj kev txwv ntawm kev loj hlob, lub hom phiaj ntawm peb txoj kev tshawb fawb yog los tshawb nrhiav cov txheej txheem ua haujlwm. Thaum cov kab mob xws li algae raug rau cov tshuaj lossis cov ntaub ntawv tsis paub txog lawv cov ecosystem, lawv yuav teb tau ntau txoj hauv kev58,59. Thaum tsis muaj cov hlau oxides lom, microalgae tuaj yeem noj lawv tus kheej, cia lawv loj hlob tas mus li60. Tom qab noj cov tshuaj lom, cov txheej txheem tiv thaiv yuav raug qhib, xws li hloov pauv duab lossis daim ntawv. Qhov ua tau ntawm kev nqus kuj yuav tsum tau txiav txim siab58,59. Qhov tseem ceeb, txhua lub cim ntawm cov txheej txheem tiv thaiv yog qhov qhia meej txog qhov kev lom ntawm cov tshuaj sim. Yog li ntawd, hauv peb txoj haujlwm ntxiv, peb tau tshawb xyuas qhov kev sib cuam tshuam ntawm qhov chaw ntawm SL Nb-MXene nanoflakes thiab microalgae los ntawm SEM thiab qhov ua tau ntawm Nb-based MXene los ntawm X-ray fluorescence spectroscopy (XRF). Nco ntsoov tias SEM thiab XRF kev tshuaj xyuas tsuas yog ua tiav ntawm qhov siab tshaj plaws ntawm MXene los daws cov teeb meem kev lom ntawm kev ua haujlwm.
Cov txiaj ntsig SEM tau pom nyob rau hauv daim duab 4. Cov hlwb microalgae uas tsis tau kho (saib daim duab 4a, cov qauv siv) qhia meej meej txog cov qauv R. subcapitata thiab cov duab zoo li croissant. Cov hlwb zoo li tiaj tus thiab tsis muaj kev teeb tsa zoo. Qee cov hlwb microalgae sib tshooj thiab sib koom ua ke, tab sis qhov no tej zaum yog vim cov txheej txheem npaj cov qauv. Feem ntau, cov hlwb microalgae ntshiab muaj qhov chaw du thiab tsis pom muaj kev hloov pauv morphological.
Cov duab SEM qhia txog kev sib cuam tshuam ntawm qhov chaw ntawm cov microalgae ntsuab thiab MXene nanosheets tom qab 72 teev ntawm kev sib cuam tshuam ntawm qhov concentration siab heev (100 mg L-1). (a) Cov microalgae ntsuab tsis tau kho tom qab kev sib cuam tshuam nrog SL (b) Nb2CTx thiab (c) Nb4C3TX MXenes. Nco ntsoov tias cov Nb-MXene nanoflakes tau cim nrog cov xub liab. Rau kev sib piv, cov duab los ntawm lub tshuab microscope optical kuj tau ntxiv.
Qhov sib txawv, cov hlwb microalgae uas tau txais los ntawm SL Nb-MXene nanoflakes raug puas tsuaj (saib daim duab 4b, c, cov xub liab). Hauv qhov xwm txheej ntawm Nb2CTx MXene (Daim duab 4b), microalgae feem ntau loj hlob nrog cov nanoscales ob-seem txuas, uas tuaj yeem hloov lawv cov morphology. Qhov tseem ceeb, peb kuj tau pom cov kev hloov pauv no hauv qab lub teeb microscopy (saib SI Daim Duab S11 kom paub meej ntxiv). Qhov kev hloov pauv morphological no muaj lub hauv paus hauv lub cev ntawm microalgae thiab lawv lub peev xwm los tiv thaiv lawv tus kheej los ntawm kev hloov pauv cell morphology, xws li nce cell ntim61. Yog li ntawd, nws yog ib qho tseem ceeb los xyuas cov lej ntawm cov hlwb microalgae uas tau sib cuag nrog Nb-MXenes. Kev tshawb fawb SEM qhia tau tias kwv yees li 52% ntawm cov hlwb microalgae tau raug rau Nb-MXenes, thaum 48% ntawm cov hlwb microalgae no zam kev sib cuag. Rau SL Nb4C3Tx MXene, microalgae sim zam kev sib cuag nrog MXene, yog li ntawd lawv nrhiav chaw thiab loj hlob los ntawm ob-seem nanoscales (Daim duab 4c). Txawm li cas los xij, peb tsis tau pom qhov nkag mus ntawm nanoscales rau hauv cov hlwb microalgae thiab lawv qhov kev puas tsuaj.
Kev tiv thaiv tus kheej kuj yog ib qho kev teb raws sijhawm rau qhov kev thaiv ntawm photosynthesis vim yog qhov adsorption ntawm cov khoom me me ntawm qhov chaw ntawm lub cell thiab qhov hu ua shading (shading) effect62. Nws yog qhov tseeb tias txhua yam khoom (piv txwv li, Nb-MXene nanoflakes) uas nyob nruab nrab ntawm microalgae thiab lub teeb qhov chaw txwv qhov ntau ntawm lub teeb uas nqus los ntawm chloroplasts. Txawm li cas los xij, peb tsis muaj kev tsis ntseeg tias qhov no muaj kev cuam tshuam loj rau cov txiaj ntsig tau txais. Raws li peb cov kev soj ntsuam microscopic qhia, 2D nanoflakes tsis tau qhwv tag nrho lossis lo rau ntawm qhov chaw ntawm microalgae, txawm tias thaum cov hlwb microalgae tau sib cuag nrog Nb-MXenes. Hloov chaw, nanoflakes tau tig mus rau cov hlwb microalgae yam tsis tau npog lawv qhov chaw. Xws li ib pawg ntawm nanoflakes / microalgae tsis tuaj yeem txwv qhov ntau ntawm lub teeb uas nqus los ntawm cov hlwb microalgae. Ntxiv mus, qee qhov kev tshawb fawb tau ua pov thawj txog kev txhim kho hauv kev nqus lub teeb los ntawm cov kab mob photosynthetic nyob rau hauv qhov muaj ob-seem nanomaterials63,64,65,66.
Vim tias cov duab SEM tsis tuaj yeem lees paub ncaj qha tias cov hlwb microalgae nqus niobium, peb txoj kev tshawb fawb ntxiv tau tig mus rau X-ray fluorescence (XRF) thiab X-ray photoelectron spectroscopy (XPS) kev tshuaj xyuas kom meej qhov teeb meem no. Yog li ntawd, peb piv qhov muaj zog ntawm Nb peaks ntawm cov qauv microalgae uas tsis cuam tshuam nrog MXenes, MXene nanoflakes detached ntawm qhov chaw ntawm cov hlwb microalgae, thiab cov hlwb microalgal tom qab tshem tawm cov MXenes txuas. Nws tsim nyog sau cia tias yog tias tsis muaj Nb uptake, tus nqi Nb tau los ntawm cov hlwb microalgae yuav tsum yog xoom tom qab tshem tawm cov nanoscales txuas. Yog li ntawd, yog tias Nb uptake tshwm sim, ob qho tib si XRF thiab XPS cov txiaj ntsig yuav tsum qhia meej Nb peak.
Hauv qhov xwm txheej ntawm XRF spectra, cov qauv microalgae qhia tau tias Nb peaks rau SL Nb2CTx thiab Nb4C3Tx MXene tom qab kev sib cuam tshuam nrog SL Nb2CTx thiab Nb4C3Tx MXene (saib daim duab 5a, kuj nco ntsoov tias cov txiaj ntsig rau MAX thiab ML MXenes tau qhia hauv SI, Figs S12–C17). Qhov nthuav yog, qhov muaj zog ntawm Nb peak yog tib yam hauv ob qho xwm txheej (cov kab liab hauv daim duab 5a). Qhov no qhia tau tias cov algae tsis tuaj yeem nqus tau ntau Nb, thiab lub peev xwm siab tshaj plaws rau Nb accumulation tau ua tiav hauv cov cell, txawm hais tias ob zaug ntau Nb4C3Tx MXene tau txuas rau cov microalgae cell (cov kab xiav hauv daim duab 5a). Qhov tseem ceeb, lub peev xwm ntawm microalgae los nqus cov hlau nyob ntawm qhov concentration ntawm cov hlau oxides hauv ib puag ncig 67,68. Shamshada et al.67 pom tias lub peev xwm nqus tau ntawm cov algae dej qab zib txo qis nrog kev nce pH. Raize et al.68 tau sau tseg tias lub peev xwm ntawm seaweed los nqus cov hlau yog li 25% siab dua rau Pb2+ dua li rau Ni2+.
(a) Cov txiaj ntsig XRF ntawm kev nqus Nb los ntawm cov hlwb microalgae ntsuab uas tau muab tso rau hauv qhov concentration siab heev ntawm SL Nb-MXenes (100 mg L-1) rau 72 teev. Cov txiaj ntsig qhia txog qhov muaj α hauv cov hlwb microalgae ntshiab (cov qauv tswj, cov kem grey), 2D nanoflakes cais tawm ntawm cov hlwb microalgae saum npoo av (cov kem xiav), thiab cov hlwb microalgae tom qab sib cais 2D nanoflakes ntawm qhov chaw (cov kem liab). Tus nqi ntawm cov elemental Nb, (b) feem pua ​​ntawm cov tshuaj lom neeg sib xyaw ntawm cov khoom siv microalgae organic (C=O thiab CHx/C–O) thiab Nb oxides uas muaj nyob hauv cov hlwb microalgae tom qab muab tso rau hauv nrog SL Nb-MXenes, (c–e) Kev sib phim ntawm lub ncov compositional ntawm XPS SL Nb2CTx spectra thiab (fh) SL Nb4C3Tx MXene uas tau muab tso rau hauv los ntawm cov hlwb microalgae.
Yog li ntawd, peb xav tias Nb tuaj yeem raug nqus los ntawm cov hlwb algal hauv daim ntawv ntawm oxides. Txhawm rau sim qhov no, peb tau ua cov kev tshawb fawb XPS ntawm MXenes Nb2CTx thiab Nb4C3TX thiab cov hlwb algae. Cov txiaj ntsig ntawm kev sib cuam tshuam ntawm microalgae nrog Nb-MXenes thiab MXenes cais los ntawm cov hlwb algae tau pom hauv Figs. 5b. Raws li xav tau, peb tau pom Nb 3d peaks hauv cov qauv microalgae tom qab tshem tawm MXene ntawm qhov chaw ntawm microalgae. Kev txiav txim siab ntau ntawm C = O, CHx / CO, thiab Nb oxides tau suav raws li Nb 3d, O 1s, thiab C 1s spectra tau txais nrog Nb2CTx SL (Daim Duab 5c-e) thiab Nb4C3Tx SL (Daim Duab 5c-e). ) tau txais los ntawm incubated microalgae. Daim Duab 5f-h) MXenes. Rooj S1-3 qhia cov ntsiab lus ntawm cov kev txwv siab tshaj plaws thiab tag nrho cov tshuaj lom neeg los ntawm qhov haum. Nws yog ib qho tseem ceeb uas cov cheeb tsam Nb 3d ntawm Nb2CTx SL thiab Nb4C3Tx SL (Daim Duab 5c, f) sib raug rau ib qho khoom Nb2O5. Ntawm no, peb tsis pom muaj cov ncov ntsig txog MXene hauv cov spectra, qhia tias cov hlwb microalgae tsuas yog nqus cov oxide ntawm Nb. Tsis tas li ntawd, peb kwv yees cov spectrum C 1 s nrog cov khoom C-C, CHx/C-O, C=O, thiab –COOH. Peb tau muab cov ncov CHx/C-O thiab C=O rau cov organic pab txhawb nqa ntawm cov hlwb microalgae. Cov khoom organic no suav txog 36% thiab 41% ntawm cov ncov C 1s hauv Nb2CTx SL thiab Nb4C3TX SL, raws li. Tom qab ntawd peb tau teeb tsa cov spectra O 1s ntawm SL Nb2CTx thiab SL Nb4C3TX nrog Nb2O5, cov khoom organic ntawm microalgae (CHx/CO), thiab cov dej uas nqus tau saum npoo av.
Thaum kawg, cov txiaj ntsig XPS qhia meej meej txog daim ntawv ntawm Nb, tsis yog nws qhov muaj xwb. Raws li qhov chaw ntawm Nb 3d teeb liab thiab cov txiaj ntsig ntawm deconvolution, peb paub tseeb tias Nb tsuas yog nqus tau hauv daim ntawv ntawm oxides thiab tsis yog ions lossis MXene nws tus kheej. Tsis tas li ntawd, cov txiaj ntsig XPS qhia tau hais tias cov hlwb microalgae muaj peev xwm ntau dua los nqus Nb oxides los ntawm SL Nb2CTx piv rau SL Nb4C3TX MXene.
Txawm hais tias peb cov txiaj ntsig Nb uptake yog qhov zoo kawg thiab tso cai rau peb txheeb xyuas MXene degradation, tsis muaj txoj hauv kev muaj los taug qab cov kev hloov pauv morphological hauv 2D nanoflakes. Yog li ntawd, peb kuj tau txiav txim siab los tsim ib txoj hauv kev tsim nyog uas tuaj yeem teb ncaj qha rau txhua qhov kev hloov pauv tshwm sim hauv 2D Nb-MXene nanoflakes thiab microalgae hlwb. Nws yog ib qho tseem ceeb uas yuav tsum nco ntsoov tias peb xav tias yog tias cov tsiaj sib cuam tshuam dhau los ntawm kev hloov pauv, kev rhuav tshem lossis defragmentation, qhov no yuav tsum sai sai qhia nws tus kheej ua kev hloov pauv hauv cov duab tsis xws luag, xws li txoj kab uas hla ntawm thaj chaw sib npaug, puag ncig, Feret dav, lossis Feret ntev. Txij li thaum cov kev ntsuas no yog qhov tsim nyog rau kev piav qhia txog cov khoom me me lossis ob-seem nanoflakes, lawv txoj kev taug qab los ntawm kev tshuaj xyuas cov duab ntawm cov khoom me me yuav muab cov ntaub ntawv tseem ceeb rau peb txog kev hloov pauv morphological ntawm SL Nb-MXene nanoflakes thaum lub sijhawm txo qis.
Cov txiaj ntsig tau txais tau pom hauv Daim Duab 6. Rau kev sib piv, peb kuj tau sim cov theem MAX thawj thiab ML-MXenes (saib SI Cov Duab S18 thiab S19). Kev tshuaj xyuas dynamic ntawm cov duab ntawm cov khoom me me qhia tau hais tias txhua yam duab ntawm ob lub Nb-MXene SLs tau hloov pauv ntau tom qab kev sib cuam tshuam nrog microalgae. Raws li qhia los ntawm qhov sib npaug ntawm thaj chaw voj voog (Daim Duab 6a, b), qhov txo qis ntawm qhov siab tshaj plaws ntawm cov feem ntawm cov nanoflakes loj qhia tau hais tias lawv feem ntau yuav lwj mus rau hauv cov khoom me me. Ntawm daim duab 6c, d qhia txog kev txo qis ntawm cov ncov uas cuam tshuam nrog qhov loj me ntawm cov flakes (kev ntev ntawm cov nanoflakes), qhia txog kev hloov pauv ntawm 2D nanoflakes mus rau hauv cov duab zoo li cov khoom me me. Daim Duab 6e-h qhia txog qhov dav thiab ntev ntawm Feret, feem. Feret dav thiab ntev yog cov kev sib txuas ua ke thiab yog li ntawd yuav tsum tau xav txog ua ke. Tom qab kev sib xyaw ntawm 2D Nb-MXene nanoflakes nyob rau hauv qhov muaj microalgae, lawv cov Feret correlation peaks hloov pauv thiab lawv qhov muaj zog txo qis. Raws li cov txiaj ntsig no ua ke nrog morphology, XRF thiab XPS, peb xaus lus tias cov kev hloov pauv uas tau pom muaj feem cuam tshuam nrog oxidation raws li oxidized MXenes ua rau wrinkled thiab tawg ua tej daim me me thiab cov khoom me me oxide spherical 69,70.
Kev Tshuaj Xyuas Txog Kev Hloov Pauv MXene Tom Qab Muaj Kev Sib Cuam Tshuam Nrog Cov Microalgae Ntsuab. Kev Tshuaj Xyuas Cov Duab Dynamic Particle suav nrog cov yam ntxwv xws li (a, b) txoj kab uas hla ntawm thaj chaw sib npaug, (c, d) puag ncig, (e, f) Qhov dav Feret thiab (g, h) Qhov ntev Feret. Txog qhov kawg no, ob qho qauv microalgae siv tau tshuaj xyuas ua ke nrog thawj SL Nb2CTx thiab SL Nb4C3Tx MXenes, SL Nb2CTx thiab SL Nb4C3Tx MXenes, cov microalgae uas lwj, thiab kho cov microalgae SL Nb2CTx thiab SL Nb4C3Tx MXenes. Cov xub liab qhia txog kev hloov pauv ntawm cov yam ntxwv ntawm cov nanoflakes ob-seem uas tau kawm.
Vim tias kev tshuaj xyuas cov duab parameter yog qhov txhim khu kev qha heev, nws kuj tseem tuaj yeem qhia txog kev hloov pauv morphological hauv cov hlwb microalgae. Yog li ntawd, peb tau tshuaj xyuas qhov sib npaug ntawm thaj chaw voj voog, qhov puag ncig, thiab Feret dav / ntev ntawm cov hlwb microalgae ntshiab thiab cov hlwb tom qab kev sib cuam tshuam nrog 2D Nb nanoflakes. Ntawm daim duab 6a-h qhia kev hloov pauv hauv cov duab parameters ntawm cov hlwb algae, raws li pov thawj los ntawm kev txo qis ntawm qhov siab tshaj plaws thiab kev hloov pauv ntawm maxima mus rau qhov siab dua. Tshwj xeeb, cov txheej txheem puag ncig ntawm cov hlwb tau qhia txog kev txo qis hauv cov hlwb ntev thiab kev nce hauv cov hlwb kheej kheej (Daim duab 6a, b). Tsis tas li ntawd, Feret cell dav nce los ntawm ntau micrometers tom qab kev sib cuam tshuam nrog SL Nb2CTx MXene (Daim duab 6e) piv rau SL Nb4C3TX MXene (Daim duab 6f). Peb xav tias qhov no yuav yog vim muaj zog ntawm Nb oxides los ntawm microalgae thaum kev sib cuam tshuam nrog Nb2CTx SR. Kev txuas tsawg dua ntawm Nb flakes rau lawv qhov chaw tuaj yeem ua rau cov hlwb loj hlob nrog qhov cuam tshuam tsawg kawg nkaus.
Peb cov kev soj ntsuam ntawm kev hloov pauv ntawm cov yam ntxwv ntawm cov duab thiab qhov loj ntawm microalgae ua kom tiav lwm cov kev tshawb fawb. Cov microalgae ntsuab tuaj yeem hloov lawv cov morphology los teb rau kev ntxhov siab ib puag ncig los ntawm kev hloov pauv qhov loj ntawm lub hlwb, cov duab lossis cov metabolism61. Piv txwv li, kev hloov pauv qhov loj ntawm cov hlwb ua rau kev nqus cov as-ham71. Cov hlwb algae me dua qhia txog kev nqus cov as-ham qis dua thiab kev loj hlob qeeb. Ntawm qhov tod tes, cov hlwb loj dua feem ntau noj ntau cov as-ham, uas tom qab ntawd tau tso rau hauv cov hlwb72,73. Machado thiab Soares pom tias cov tshuaj fungicide triclosan tuaj yeem ua rau cov hlwb loj dua. Lawv kuj pom muaj kev hloov pauv tob hauv cov duab ntawm cov algae74. Tsis tas li ntawd, Yin et al.9 kuj tau qhia txog kev hloov pauv morphological hauv algae tom qab raug rau cov graphene oxide nanocomposites txo qis. Yog li ntawd, nws yog qhov tseeb tias cov kev hloov pauv loj / cov duab ntawm microalgae yog tshwm sim los ntawm qhov muaj MXene. Txij li thaum qhov kev hloov pauv loj thiab cov duab no yog qhov qhia txog kev hloov pauv hauv kev nqus cov as-ham, peb ntseeg tias kev tshuaj xyuas ntawm cov yam ntxwv loj thiab cov duab dhau sijhawm tuaj yeem qhia txog kev nqus ntawm niobium oxide los ntawm microalgae nyob rau hauv qhov muaj Nb-MXenes.
Ntxiv mus, MXenes tuaj yeem raug oxidized nyob rau hauv lub xub ntiag ntawm algae. Dalai et al.75 tau pom tias cov morphology ntawm cov algae ntsuab raug rau nano-TiO2 thiab Al2O376 tsis sib xws. Txawm hais tias peb cov kev soj ntsuam zoo ib yam li kev tshawb fawb tam sim no, nws tsuas yog cuam tshuam rau kev tshawb fawb ntawm cov teebmeem ntawm bioremediation hauv cov nqe lus ntawm MXene degradation khoom nyob rau hauv lub xub ntiag ntawm 2D nanoflakes thiab tsis yog nanoparticles. Txij li thaum MXenes tuaj yeem degrade rau hauv cov hlau oxides,31,32,77,78 nws yog qhov tsim nyog los xav tias peb Nb nanoflakes kuj tuaj yeem tsim Nb oxides tom qab cuam tshuam nrog cov hlwb microalgae.
Yuav kom piav qhia txog kev txo qis ntawm 2D-Nb nanoflakes los ntawm kev siv lub tshuab decomposition raws li cov txheej txheem oxidation, peb tau ua kev tshawb fawb siv high-resolution transmission electron microscopy (HRTEM) (Daim duab 7a, b) thiab X-ray photoelectron spectroscopy (XPS) (Daim duab 7). 7c-i thiab cov lus qhia S4-5). Ob txoj hauv kev no yog qhov tsim nyog rau kev kawm txog kev oxidation ntawm cov ntaub ntawv 2D thiab ua kom sib haum. HRTEM muaj peev xwm tshuaj xyuas qhov kev puas tsuaj ntawm cov qauv txheej ob-seem thiab qhov tshwm sim tom qab ntawm cov hlau oxide nanoparticles, thaum XPS rhiab heev rau cov ntawv cog lus saum npoo. Rau lub hom phiaj no, peb tau sim 2D Nb-MXene nanoflakes rho tawm los ntawm microalgae cell dispersions, uas yog, lawv cov duab tom qab kev sib cuam tshuam nrog microalgae cell (saib Daim duab 7).
Cov duab HRTEM qhia txog cov morphology ntawm oxidized (a) SL Nb2CTx thiab (b) SL Nb4C3Tx MXenes, XPS cov txiaj ntsig tshuaj xyuas qhia (c) cov khoom sib xyaw ntawm cov khoom oxide tom qab txo qis, (d-f) qhov sib phim ntawm cov khoom ntawm XPS spectra ntawm SL Nb2CTx thiab (g-i) Nb4C3Tx SL kho nrog cov microalgae ntsuab.
Cov kev tshawb fawb HRTEM tau lees paub qhov oxidation ntawm ob hom Nb-MXene nanoflakes. Txawm hais tias cov nanoflakes khaws cia lawv cov morphology ob-seem rau qee qhov, oxidation ua rau muaj ntau cov nanoparticles npog qhov chaw ntawm MXene nanoflakes (saib daim duab 7a, b). XPS kev tshuaj xyuas ntawm c Nb 3d thiab O 1s cov cim qhia tias Nb oxides tau tsim nyob rau hauv ob qho tib si. Raws li pom hauv Daim Duab 7c, 2D MXene Nb2CTx thiab Nb4C3TX muaj Nb 3d cov cim qhia tias muaj NbO thiab Nb2O5 oxides, thaum O 1s cov cim qhia txog tus lej ntawm O-Nb bonds cuam tshuam nrog kev ua haujlwm ntawm 2D nanoflake nto. Peb pom tias Nb oxide kev koom tes yog qhov tseem ceeb piv rau Nb-C thiab Nb3 + -O.
Hauv daim duab 7g–i qhia txog XPS spectra ntawm Nb 3d, C 1s, thiab O 1s SL Nb2CTx (saib daim duab 7d–f) thiab SL Nb4C3TX MXene cais tawm ntawm cov hlwb microalgae. Cov ntsiab lus ntawm Nb-MXenes peak parameters tau muab rau hauv Cov Lus Qhia S4–5, raws li. Peb thawj zaug tshuaj xyuas cov khoom sib xyaw ntawm Nb 3d. Tsis zoo li Nb nqus los ntawm cov hlwb microalgae, hauv MXene cais tawm ntawm cov hlwb microalgae, tsis suav nrog Nb2O5, lwm yam khoom tau pom. Hauv Nb2CTx SL, peb tau pom qhov kev koom tes ntawm Nb3+-O hauv qhov ntau ntawm 15%, thaum seem ntawm Nb 3d spectrum tau tswj hwm los ntawm Nb2O5 (85%). Tsis tas li ntawd, SL Nb4C3TX qauv muaj Nb-C (9%) thiab Nb2O5 (91%) cov khoom. Ntawm no Nb-C los ntawm ob txheej atomic sab hauv ntawm cov hlau carbide hauv Nb4C3Tx SR. Tom qab ntawd peb kos cov C 1s spectra rau plaub yam sib txawv, zoo li peb tau ua hauv cov qauv sab hauv. Raws li xav tau, C 1s spectrum yog dominated los ntawm graphitic carbon, ua raws li kev koom tes los ntawm cov organic particles (CHx/CO thiab C = O) los ntawm microalgae hlwb. Tsis tas li ntawd, hauv O 1s spectrum, peb tau pom kev koom tes ntawm cov organic hom ntawm microalgae hlwb, niobium oxide, thiab dej adsorbed.
Ntxiv rau, peb tau tshawb xyuas seb Nb-MXenes cleavage puas cuam tshuam nrog qhov muaj cov reactive oxygen species (ROS) hauv cov khoom noj khoom haus thiab / lossis cov hlwb microalgae. Txog qhov kawg no, peb tau soj ntsuam cov theem ntawm singlet oxygen (1O2) hauv cov khoom noj khoom haus thiab intracellular glutathione, ib qho thiol uas ua haujlwm ua antioxidant hauv microalgae. Cov txiaj ntsig tau pom hauv SI (Daim Duab S20 thiab S21). Cov kab lis kev cai nrog SL Nb2CTx thiab Nb4C3TX MXenes tau ua cim los ntawm qhov txo qis ntawm 1O2 (saib Daim Duab S20). Hauv qhov xwm txheej ntawm SL Nb2CTx, MXene 1O2 raug txo kom txog li 83%. Rau cov kab lis kev cai microalgae siv SL, Nb4C3TX 1O2 txo qis ntau dua, mus rau 73%. Qhov nthuav yog, kev hloov pauv hauv 1O2 tau qhia tib yam li cov nyhuv inhibitory-stimulatory uas tau pom yav dhau los (saib Daim Duab 3). Nws tuaj yeem sib cav tias kev sib xyaw ua ke hauv lub teeb ci tuaj yeem hloov pauv photooxidation. Txawm li cas los xij, cov txiaj ntsig ntawm kev tshuaj xyuas kev tswj hwm qhia txog cov theem yuav luag tas li ntawm 1O2 thaum lub sijhawm sim (Daim Duab S22). Hauv cov ntaub ntawv ntawm cov theem ROS hauv lub hlwb, peb kuj tau pom tib qho kev poob qis (saib Daim Duab S21). Thaum pib, cov theem ntawm ROS hauv cov hlwb microalgae uas cog qoob loo hauv qhov muaj Nb2CTx thiab Nb4C3Tx SLs tau dhau cov theem pom hauv cov kab lis kev cai ntshiab ntawm microalgae. Txawm li cas los xij, thaum kawg, nws zoo li tias microalgae tau hloov kho rau qhov muaj ob qho tib si Nb-MXenes, vim tias ROS theem txo qis mus rau 85% thiab 91% ntawm cov theem ntsuas hauv cov kab lis kev cai ntshiab ntawm microalgae uas tau txhaj tshuaj nrog SL Nb2CTx thiab Nb4C3TX, raws li. Qhov no yuav qhia tau tias microalgae xav tias xis nyob dua li lub sijhawm nyob rau hauv qhov muaj Nb-MXene dua li hauv cov khoom noj khoom haus ib leeg.
Cov kab me me yog ib pawg ntawm ntau yam kab mob photosynthetic. Thaum lub sijhawm photosynthesis, lawv hloov cov pa roj carbon dioxide (CO2) hauv huab cua mus rau hauv cov pa roj carbon organic. Cov khoom ntawm photosynthesis yog glucose thiab oxygen79. Peb xav tias cov pa oxygen uas tsim los ua lub luag haujlwm tseem ceeb hauv kev oxidation ntawm Nb-MXenes. Ib qho kev piav qhia rau qhov no yog tias qhov sib txawv ntawm aeration parameter yog tsim ntawm qhov qis thiab siab ib feem ntawm cov pa oxygen sab nraud thiab sab hauv Nb-MXene nanoflakes. Qhov no txhais tau tias txhua qhov chaw muaj thaj chaw ntawm cov pa oxygen sib txawv, thaj chaw uas muaj qib qis tshaj plaws yuav tsim cov anode 80, 81, 82. Ntawm no, cov microalgae pab txhawb rau kev tsim cov hlwb sib txawv ntawm qhov chaw ntawm MXene flakes, uas tsim cov pa oxygen vim lawv cov khoom photosynthetic. Yog li ntawd, cov khoom biocorrosion (hauv qhov no, niobium oxides) raug tsim. Lwm qhov yog tias microalgae tuaj yeem tsim cov organic acids uas raug tso tawm rau hauv dej83,84. Yog li ntawd, ib puag ncig uas muaj kev kub ntxhov tau tsim, yog li hloov cov Nb-MXenes. Tsis tas li ntawd, microalgae tuaj yeem hloov pH ntawm ib puag ncig mus rau alkaline vim yog kev nqus ntawm carbon dioxide, uas kuj tseem tuaj yeem ua rau xeb79.
Qhov tseem ceeb tshaj, qhov tsaus ntuj/lub teeb photoperiod siv hauv peb txoj kev tshawb fawb yog qhov tseem ceeb rau kev nkag siab txog cov txiaj ntsig tau txais. Qhov no tau piav qhia meej hauv Djemai-Zoghlache et al. 85 Lawv txhob txwm siv 12/12 teev photoperiod los qhia txog biocorrosion cuam tshuam nrog biofouling los ntawm cov kab mob liab microalgae Porphyridium purpureum. Lawv qhia tias lub photoperiod cuam tshuam nrog kev hloov pauv ntawm lub peev xwm tsis muaj biocorrosion, qhia nws tus kheej ua pseudoperiodic oscillations nyob ib puag ncig 24:00. Cov kev soj ntsuam no tau lees paub los ntawm Dowling et al. 86 Lawv tau ua qauv qhia txog photosynthetic biofilms ntawm cyanobacteria Anabaena. Cov pa oxygen yaj yog tsim nyob rau hauv qhov kev ua ntawm lub teeb, uas cuam tshuam nrog kev hloov pauv lossis kev hloov pauv hauv lub peev xwm biocorrosion dawb. Qhov tseem ceeb ntawm lub photoperiod yog hais txog qhov tseeb tias lub peev xwm dawb rau biocorrosion nce hauv theem teeb thiab txo qis hauv theem tsaus ntuj. Qhov no yog vim cov pa oxygen tsim los ntawm photosynthetic microalgae, uas cuam tshuam rau cathodic reaction los ntawm qhov siab ib nrab tsim nyob ze ntawm cov electrodes87.
Ntxiv rau, Fourier transform infrared spectroscopy (FTIR) tau ua tiav los nrhiav seb puas muaj kev hloov pauv tshwm sim hauv cov tshuaj lom neeg ntawm cov hlwb microalgae tom qab kev sib cuam tshuam nrog Nb-MXenes. Cov txiaj ntsig tau txais no yog qhov nyuaj thiab peb nthuav qhia lawv hauv SI (Cov duab S23-S25, suav nrog cov txiaj ntsig ntawm theem MAX thiab ML MXenes). Hauv ntej, cov spectra siv tau ntawm microalgae muab cov ntaub ntawv tseem ceeb rau peb txog cov yam ntxwv tshuaj lom neeg ntawm cov kab mob no. Cov kev co feem ntau no nyob ntawm qhov zaus ntawm 1060 cm-1 (CO), 1540 cm-1, 1640 cm-1 (C = C), 1730 cm-1 (C = O), 2850 cm-1, 2920 cm-1. ib. 1 1 (C-H) thiab 3280 cm-1 (O-H). Rau SL Nb-MXenes, peb pom CH-bond stretching kos npe uas sib xws nrog peb txoj kev kawm yav dhau los 38. Txawm li cas los xij, peb tau pom tias qee qhov ntxiv peaks cuam tshuam nrog C = C thiab CH bonds ploj mus. Qhov no qhia tau hais tias cov tshuaj lom neeg ntawm microalgae yuav hloov pauv me ntsis vim muaj kev cuam tshuam nrog SL Nb-MXenes.
Thaum xav txog qhov kev hloov pauv uas ua tau hauv biochemistry ntawm microalgae, qhov kev sib sau ua ke ntawm cov inorganic oxides, xws li niobium oxide, yuav tsum tau rov xav txog59. Nws koom nrog kev nqus cov hlau los ntawm qhov chaw ntawm lub cell, lawv txoj kev thauj mus rau hauv cytoplasm, lawv txoj kev sib raug zoo nrog cov pab pawg carboxyl intracellular, thiab lawv txoj kev sib sau ua ke hauv microalgae polyphosphosomes20,88,89,90. Tsis tas li ntawd, kev sib raug zoo ntawm microalgae thiab cov hlau yog tswj los ntawm cov pab pawg ua haujlwm ntawm cov cell. Vim li no, kev nqus kuj nyob ntawm microalgae nto chemistry, uas yog qhov nyuaj heev9,91. Feem ntau, raws li xav tau, cov tshuaj lom neeg ntawm cov microalgae ntsuab hloov me ntsis vim yog kev nqus ntawm Nb oxide.
Qhov txaus nyiam yog, qhov kev txwv tsis pub microalgae pib pom tau rov qab tau raws sijhawm. Raws li peb tau pom, microalgae tau kov yeej qhov kev hloov pauv ib puag ncig thawj zaug thiab thaum kawg rov qab mus rau qhov kev loj hlob ib txwm thiab txawm tias nce ntxiv. Kev tshawb fawb ntawm lub peev xwm zeta qhia tau tias muaj kev ruaj khov siab thaum qhia rau hauv cov khoom noj khoom haus. Yog li, qhov kev sib cuam tshuam ntawm qhov chaw ntawm cov hlwb microalgae thiab Nb-MXene nanoflakes tau khaws cia thoob plaws hauv kev sim txo qis. Hauv peb qhov kev tshuaj xyuas ntxiv, peb sau cov txheej txheem tseem ceeb ntawm kev ua haujlwm hauv qab tus cwj pwm zoo kawg no ntawm microalgae.
Kev soj ntsuam SEM tau qhia tias cov microalgae feem ntau txuas nrog Nb-MXenes. Siv kev tshuaj xyuas duab dynamic, peb paub tseeb tias qhov cuam tshuam no ua rau muaj kev hloov pauv ntawm ob-seem Nb-MXene nanoflakes mus rau hauv ntau lub pob zeb spherical, yog li qhia tau tias qhov kev rhuav tshem ntawm nanoflakes yog txuam nrog lawv cov oxidation. Txhawm rau sim peb qhov kev xav, peb tau ua ntau yam kev tshawb fawb txog cov khoom siv thiab biochemical. Tom qab kev sim, cov nanoflakes maj mam oxidized thiab decomposed rau hauv NbO thiab Nb2O5 cov khoom, uas tsis ua rau muaj kev hem thawj rau cov microalgae ntsuab. Siv FTIR kev soj ntsuam, peb tsis pom muaj kev hloov pauv tseem ceeb hauv cov tshuaj lom neeg ntawm microalgae incubated nyob rau hauv qhov muaj 2D Nb-MXene nanoflakes. Xav txog qhov ua tau ntawm kev nqus ntawm niobium oxide los ntawm microalgae, peb tau ua qhov kev tshuaj xyuas X-ray fluorescence. Cov txiaj ntsig no qhia meej meej tias cov microalgae kawm noj niobium oxides (NbO thiab Nb2O5), uas tsis muaj tshuaj lom rau cov microalgae kawm.