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Hauv kev ua haujlwm no, rGO / nZVI composites tau tsim ua thawj zaug uas siv cov txheej txheem yooj yim thiab ib puag ncig tus phooj ywg siv Sophora yellowish nplooj extract raws li tus neeg sawv cev txo qis thiab stabilizer kom ua raws li cov hauv paus ntsiab lus ntawm "ntsuab" chemistry, xws li tshuaj lom neeg tsis zoo. Ntau cov cuab yeej tau siv los ua pov thawj qhov ua tiav ntawm kev sib xyaw ua ke, xws li SEM, EDX, XPS, XRD, FTIR, thiab zeta muaj peev xwm, uas qhia tau tias muaj kev sib xyaw ua tiav. Kev tshem tawm lub peev xwm ntawm cov khoom sib xyaw tshiab thiab cov ntshiab nZVI ntawm ntau qhov pib ntau ntawm cov tshuaj tua kab mob doxycycline tau muab piv rau kev soj ntsuam cov nyhuv synergistic ntawm rGO thiab nZVI. Raws li kev tshem tawm ntawm 25mg L-1, 25 ° C thiab 0.05g, adsorptive tshem tawm tus nqi ntawm nZVI ntshiab yog 90%, thaum lub adsorptive tshem tawm tus nqi ntawm doxycycline los ntawm rGO / nZVI sib xyaw mus txog 94.6%, lees paub tias nZVI thiab rGO. . Cov txheej txheem adsorption sib haum mus rau qhov kev txiav txim thib ob thiab tau pom zoo nrog Freundlich qauv nrog qhov siab tshaj plaws adsorption muaj peev xwm ntawm 31.61 mg g-1 ntawm 25 ° C thiab pH 7. Cov txheej txheem tsim nyog rau kev tshem tawm DC tau raug npaj. Tsis tas li ntawd, qhov rov siv tau ntawm rGO / nZVI sib xyaw yog 60% tom qab rau 6 lub voj voog rov tsim dua.
Dej tsis txaus thiab muaj kuab paug tam sim no yog qhov kev hem thawj loj rau txhua lub tebchaws. Nyob rau hauv xyoo tas los no, dej paug, tshwj xeeb tshaj yog cov tshuaj tua kab mob muaj kuab paug, tau nce vim kev tsim khoom thiab kev noj ntau ntxiv thaum lub sij hawm COVID-19 kis thoob qhov txhia chaw 1,2,3. Yog li ntawd, kev txhim kho cov cuab yeej siv tau zoo rau kev tshem tawm cov tshuaj tua kab mob hauv cov dej khib nyiab yog ib txoj haujlwm ceev.
Ib qho ntawm cov tshuaj tiv thaiv semi-synthetic los ntawm pawg tetracycline yog doxycycline (DC) 4,5. Nws tau raug tshaj tawm tias DC residues hauv av thiab dej saum npoo av tsis tuaj yeem metabolized, tsuas yog 20-50% metabolized thiab tus so yog tso tawm rau hauv ib puag ncig, ua rau muaj teeb meem loj rau ib puag ncig thiab kev noj qab haus huv6.
Kev cuam tshuam rau DC ntawm qib qis tuaj yeem tua cov kab mob hauv dej photosynthetic, hem kom kis tau cov kab mob tua kab mob, thiab ua rau muaj kev tiv thaiv kab mob, yog li cov kab mob no yuav tsum tau muab tshem tawm ntawm cov dej khib nyiab. Lub ntuj degradation ntawm DC hauv dej yog txheej txheem qeeb heev. Cov txheej txheem physico-chemical xws li photolysis, biodegradation thiab adsorption tuaj yeem tsuas yog degrade ntawm tsawg concentrations thiab tsawg heev tus nqi 7,8. Txawm li cas los xij, kev lag luam tshaj plaws, yooj yim, ib puag ncig tus phooj ywg, yooj yim rau kev tswj thiab siv tau zoo yog adsorption9,10.
Nano zero valent iron (nZVI) yog ib yam khoom muaj zog heev uas tuaj yeem tshem tawm ntau cov tshuaj tua kab mob hauv dej, suav nrog metronidazole, diazepam, ciprofloxacin, chloramphenicol, thiab tetracycline. Qhov peev xwm no yog vim muaj cov khoom zoo heev uas nZVI muaj, xws li kev ua haujlwm siab, thaj chaw loj, thiab ntau qhov chaw sib txuas sab nraud11. Txawm li cas los xij, nZVI yog nquag mus rau aggregation nyob rau hauv aqueous xov xwm vim van der Wells rog thiab siab magnetic zog, uas txo nws cov hauj lwm zoo ntawm kev tshem tawm cov kab mob vim yog tsim ntawm oxide txheej uas inhibit lub reactivity ntawm nZVI10,12. Lub agglomeration ntawm nZVI hais tuaj yeem raug txo los ntawm kev hloov kho lawv qhov chaw nrog surfactants thiab polymers los yog los ntawm kev sib txuas nrog lwm cov ntaub ntawv nanomaterials hauv daim ntawv ntawm cov khoom sib xyaw, uas tau ua pov thawj tias yog ib txoj hauv kev zoo los txhim kho lawv cov kev ruaj ntseg hauv ib puag ncig13,14.
Graphene yog ob-dimensional carbon nanomaterial uas muaj sp2-hybridized carbon atoms teem nyob rau hauv ib tug honeycomb lattice. Nws muaj thaj tsam loj, lub zog tseem ceeb, kev ua haujlwm zoo electrocatalytic, thermal conductivity, ceev electron txav, thiab cov khoom siv tsim nyog los txhawb inorganic nanoparticles ntawm nws qhov chaw. Kev sib xyaw ua ke ntawm cov hlau nanoparticles thiab graphene tuaj yeem ua tau zoo tshaj qhov txiaj ntsig ntawm txhua tus neeg siv khoom thiab, vim nws lub cev zoo tshaj thiab tshuaj lom neeg, muab kev pom zoo ntawm nanoparticles rau kev kho dej ntau dua 15.
Cov nroj tsuag rho tawm yog lwm txoj hauv kev zoo tshaj plaws rau cov tshuaj phem txo cov neeg ua haujlwm feem ntau siv hauv kev sib xyaw ntawm cov graphene oxide (rGO) thiab nZVI vim tias lawv muaj, pheej yig, ib-kauj ruam, ib puag ncig zoo, thiab tuaj yeem siv los ua cov tshuaj txo qis. zoo li flavonoids thiab phenolic tebchaw kuj ua raws li stabilizer. Yog li ntawd, Atriplex halimus L. nplooj extract tau siv los kho thiab kaw tus neeg sawv cev rau kev sib txuas ntawm rGO / nZVI composites hauv txoj kev tshawb no. Atriplex halimus los ntawm tsev neeg Amaranthaceae yog ib tsob ntoo uas muaj nitrogen-hlub perennial nrog thaj chaw dav 16.
Raws li cov ntaub ntawv muaj, Atriplex halimus (A. halimus) yog thawj zaug siv los ua rGO / nZVI composites raws li kev lag luam thiab ib puag ncig zoo sib xws. Yog li, lub hom phiaj ntawm txoj haujlwm no muaj plaub ntu: (1) phytosynthesis ntawm rGO / nZVI thiab niam txiv nZVI sib xyaw siv A. halimus aquatic leaf extract, (2) characterization ntawm phytosynthesized composites siv ntau txoj hauv kev kom paub meej tias lawv txoj kev ua tiav, (3) ) kawm cov nyhuv synergistic ntawm rGO thiab nZVI nyob rau hauv adsorption thiab tshem tawm cov organic paug ntawm doxycycline tshuaj tua kab mob nyob rau hauv txawv cov tshuaj tiv thaiv tsis, optimize cov tej yam kev mob ntawm cov txheej txheem adsorption, (3) tshawb xyuas cov ntaub ntawv sib xyaw hauv ntau yam kev kho mob tas li tom qab lub voj voog ua haujlwm.
Doxycycline hydrochloride (DC, MM = 480.90, tshuaj formula C22H24N2O·HCl, 98%), hlau chloride hexahydrate (FeCl3.6H2O, 97%), graphite hmoov muas los ntawm Sigma-Aldrich, USA. Sodium hydroxide (NaOH, 97%), ethanol (C2H5OH, 99.9%) thiab hydrochloric acid (HCl, 37%) tau yuav los ntawm Merck, Tebchaws USA. NaCl, KCl, CaCl2, MnCl2 thiab MgCl2 tau yuav los ntawm Tianjin Comio Chemical Reagent Co., Ltd. Ob-distilled dej tau siv los npaj tag nrho cov kev daws teeb meem aqueous.
Cov neeg sawv cev ntawm A. halimus tau sau los ntawm lawv qhov chaw nyob hauv Nile Delta thiab thaj av raws ntug dej hiav txwv Mediterranean ntawm Egypt. Cov khoom cog tau raug sau ua raws li cov lus qhia hauv lub tebchaws thiab thoob ntiaj teb 17. Prof. Manal Fawzi tau txheeb xyuas cov qauv cog raws li Boulos18, thiab Lub Tsev Haujlwm Saib Xyuas Kev Tshawb Fawb Ib puag ncig ntawm Alexandria University tau tso cai sau cov nroj tsuag kawm rau kev tshawb fawb. Cov qauv vouchers muaj nyob rau ntawm Tanta University Herbarium (TANE), vouchers nos. 14 122–14 127, ib tug pej xeem herbarium uas muab kev nkag mus rau cov ntaub ntawv tso. Tsis tas li ntawd, txhawm rau tshem tawm cov plua plav lossis av, txiav cov nplooj ntawm cov nroj tsuag mus rau hauv me me, yaug 3 zaug nrog kais dej thiab distilled dej, thiab tom qab ntawd qhuav ntawm 50 ° C. Cov nroj tsuag tau crushed, 5 g ntawm hmoov zoo yog immersed nyob rau hauv 100 ml ntawm distilled dej thiab stirred ntawm 70 ° C rau 20 feeb kom tau ib tug extract. Cov extract tau ntawm Bacillus nicotianae tau lim los ntawm Whatman lim ntawv thiab khaws cia rau hauv cov kav dej huv thiab tsis muaj menyuam ntawm 4 ° C rau kev siv ntxiv.
Raws li pom hauv daim duab 1, GO yog tsim los ntawm graphite hmoov los ntawm kev hloov kho Hummers. 10 mg ntawm GO hmoov yog dispersed nyob rau hauv 50 ml ntawm deionized dej rau 30 min nyob rau hauv sonication, thiab ces 0.9 g ntawm FeCl3 thiab 2.9 g ntawm NaAc yog tov rau 60 min. 20 ml ntawm atriplex nplooj extract tau ntxiv rau cov tshuaj tov nrog nplawm thiab sab laug ntawm 80 ° C rau 8 teev. Qhov tshwm sim dub raug tshem tawm tau lim. Cov nanocomposites npaj tau ntxuav nrog ethanol thiab bidistilled dej thiab ces qhuav nyob rau hauv lub tshuab nqus tsev qhov cub ntawm 50 ° C rau 12 teev.
Schematic thiab cov duab digital ntawm ntsuab synthesis ntawm rGO / nZVI thiab nZVI complexes thiab tshem tawm DC tshuaj tua kab mob los ntawm cov dej tsis huv siv Atriplex halimus extract.
Luv luv, raws li qhia hauv daim duab 1, 10 ml ntawm cov tshuaj chloride hlau uas muaj 0.05 M Fe3 + ions tau ntxiv dropwise rau 20 ml ntawm cov nplooj nplooj iab extract rau 60 feeb nrog cua sov thiab nplawm, thiab ces cov tshuaj yog ces centrifuged ntawm 14,000 rpm (Hermle , 15,000 rpm) rau 15 min kom muab cov xim dub, uas tom qab ntawd ntxuav 3 zaug nrog ethanol thiab dej distilled thiab ces qhuav hauv qhov cub nqus tsev ntawm 60 ° C. thaum hmo ntuj.
Cog-synthesized rGO/nZVI thiab nZVI composites tau tus cwj pwm los ntawm UV-pom spectroscopy (T70/T80 series UV/Vis spectrophotometers, PG Instruments Ltd, UK) nyob rau hauv lub scanning ntau ntawm 200-800 nm. Txhawm rau txheeb xyuas qhov chaw thiab qhov loj me ntawm rGO / nZVI thiab nZVI cov khoom sib xyaw, TEM spectroscopy (JOEL, JEM-2100F, Nyiv, accelerating voltage 200 kV) tau siv. Txhawm rau ntsuas cov pab pawg ua haujlwm uas tuaj yeem koom nrog hauv cov nroj tsuag rho tawm lub luag haujlwm rau cov txheej txheem rov qab thiab ruaj khov, FT-IR spectroscopy tau ua tiav (JASCO spectrometer hauv thaj tsam ntawm 4000-600 cm-1). Tsis tas li ntawd, lub zeta muaj peev xwm analyzer (Zetasizer Nano ZS Malvern) tau siv los kawm txog tus nqi saum npoo ntawm cov khoom siv hluavtaws. Rau X-ray diffraction ntsuas ntawm hmoov nanomaterials, ib tug X-ray diffractometer (X'PERT PRO, lub Netherlands) tau siv, ua hauj lwm ntawm ib tug tam sim no (40 mA), voltage (45 kV) nyob rau hauv lub 2θ ntau yam ntawm 20 ° rau 80. ° thiab CuKa1 hluav taws xob (\(\lambda =\ ) 1.54056 Ao). Lub zog dispersive X-ray spectrometer (EDX) (tus qauv JEOL JSM-IT100) yog lub luag haujlwm rau kev kawm txog lub hauv paus muaj pes tsawg leeg thaum sau Al K-α monochromatic X-rays ntawm -10 txog 1350 eV ntawm XPS, qhov chaw loj 400 μm K-ALPHA (Thermo Fisher Scientific, USA) lub zog kis tau tus mob ntawm tag nrho cov spectrum yog 200 eV thiab nqaim spectrum yog 50 eV. Cov hmoov coj mus kuaj yog nias rau ntawm tus qauv tuav, uas yog muab tso rau hauv lub tshuab nqus tsev chamber. C 1 s spectrum tau siv los ua kev siv ntawm 284.58 eV los txiav txim siab lub zog khi.
Kev sim adsorption tau ua los ntsuas qhov ua tau zoo ntawm cov khoom siv hluavtaws rGO / nZVI nanocomposites hauv kev tshem tawm doxycycline (DC) los ntawm cov tshuaj aqueous. Kev sim adsorption tau ua nyob rau hauv 25 ml Erlenmeyer flasks ntawm qhov ceev ntawm 200 rpm ntawm lub orbital shaker (Stuart, Orbital Shaker / SSL1) ntawm 298 K. Los ntawm diluting DC Tshuag tov (1000 ppm) nrog bidistilled dej. Txhawm rau ntsuas cov txiaj ntsig ntawm rGO / nSVI ntau npaum li cas ntawm kev ua haujlwm adsorption, nanocomposites ntawm qhov hnyav sib txawv (0.01-0.07 g) tau ntxiv rau 20 ml ntawm DC tov. Txhawm rau kawm txog kinetics thiab adsorption isotherms, 0.05 g ntawm cov adsorbent yog immersed nyob rau hauv ib tug aqueous tov ntawm CD nrog thawj concentration (25-100 mg L-1). Cov nyhuv ntawm pH ntawm kev tshem tawm DC tau kawm ntawm pH (3-11) thiab qhov pib concentration ntawm 50 mg L-1 ntawm 25 ° C. Kho cov pH ntawm lub cev los ntawm kev ntxiv me me ntawm HCl lossis NaOH tov (Crison pH meter, pH meter, pH 25). Tsis tas li ntawd, qhov cuam tshuam ntawm qhov ntsuas kub ntawm qhov kev sim adsorption hauv thaj tsam ntawm 25-55 ° C tau tshawb xyuas. Cov nyhuv ntawm ionic zog ntawm cov txheej txheem adsorption tau kawm los ntawm kev ntxiv ntau qhov ntau ntawm NaCl (0.01-4 mol L-1) ntawm qhov pib concentration ntawm DC ntawm 50 mg L-1, pH 3 thiab 7), 25 ° C, thiab ib koob tshuaj adsorbent ntawm 0.05 g. Lub adsorption ntawm non-adsorbed DC tau ntsuas siv dual beam UV-Vis spectrophotometer (T70/T80 series, PG Instruments Ltd, UK) nruab nrog 1.0 cm ntev quartz cuvettes ntawm qhov siab tshaj plaws wavelengths (λmax) ntawm 270 thiab 350 nm. Qhov feem pua ntawm cov tshuaj tua kab mob DC tshem tawm (R%; Eq. 1) thiab cov nyiaj adsorption ntawm DC, qt, Eq. 2 (mg / g) tau ntsuas los ntawm kev sib npaug hauv qab no.
qhov twg % R yog DC tshem tawm muaj peev xwm (%), Co yog thawj zaug DC concentration ntawm lub sij hawm 0, thiab C yog DC concentration ntawm lub sij hawm t, feem (mg L-1).
qhov twg qe yog tus nqi ntawm DC adsorbed ib chav tsev loj ntawm cov adsorbent (mg g-1), Co thiab Ce yog cov concentrations ntawm xoom lub sij hawm thiab ntawm equilibrium, ntsig txog (mg l-1), V yog cov tshuaj ntim (l) , thiab m yog adsorption huab hwm coj reagent (g).
SEM dluab (Figs. 2A–C) qhia cov lamellar morphology ntawm lub rGO/nZVI composite nrog kheej kheej hlau nanoparticles uniformly dispersed rau nws nto, qhia tau zoo txuas ntawm nZVI NPs rau lub rGO nto. Tsis tas li ntawd, muaj qee qhov wrinkles nyob rau hauv rGO nplooj, lees paub qhov kev tshem tawm ntawm cov pa oxygen-muaj pab pawg ib txhij nrog kev kho ntawm A. halimus GO. Cov wrinkles loj no ua qhov chaw rau kev thauj khoom ntawm cov hlau NPs. nZVI dluab (Fig. 2D-F) qhia tau hais tias lub spherical hlau NPs tau tawg heev thiab tsis aggregate, uas yog vim lub txheej xwm ntawm botanical Cheebtsam ntawm cov nroj tsuag extract. Qhov loj me me sib txawv hauv 15-26 nm. Txawm li cas los xij, qee thaj tsam muaj qhov mesoporous morphology nrog cov qauv ntawm bulges thiab kab noj hniav, uas tuaj yeem muab lub peev xwm adsorption zoo ntawm nZVI, vim tias lawv tuaj yeem ua rau muaj kev cuam tshuam DC molecules ntawm nZVI. Thaum Rosa Damascus extract tau siv rau kev sib txuas ntawm nZVI, cov NPs tau txais yog inhomogeneous, nrog voids thiab sib txawv duab, uas txo lawv efficiency nyob rau hauv Cr (VI) adsorption thiab nce lub sij hawm cov tshuaj tiv thaiv 23. Cov txiaj ntsig tau zoo ib yam nrog nZVI synthesized los ntawm ntoo qhib thiab mulberry nplooj, uas feem ntau yog kheej kheej nanoparticles nrog ntau qhov ntau thiab tsawg nanometer yam tsis muaj kev sib xyaw ua ke.
SEM images of rGO/nZVI (AC), nZVI (D, E) composites and EDX patterns of nZVI/rGO (G) and nZVI (H) composites.
Lub hauv paus muaj pes tsawg leeg ntawm cov nroj tsuag-synthesized rGO / nZVI thiab nZVI composites tau kawm siv EDX (Fig. 2G, H). Cov kev tshawb fawb qhia tias nZVI yog tsim los ntawm carbon (38.29% los ntawm huab hwm coj), oxygen (47.41% los ntawm huab hwm coj) thiab hlau (11.84% los ntawm huab hwm coj), tab sis lwm yam xws li phosphorus24 kuj muaj, uas tuaj yeem tau txais los ntawm cov nroj tsuag rho tawm. Tsis tas li ntawd, qhov feem pua ntawm cov pa roj carbon ntau thiab oxygen yog vim muaj cov phytochemicals los ntawm cov nroj tsuag rho tawm hauv subsurface nZVI cov qauv. Cov ntsiab lus no sib npaug ntawm rGO tab sis nyob rau hauv qhov sib txawv: C (39.16 wt %), O (46.98 wt %) thiab Fe (10.99 wt %), EDX rGO / nZVI kuj qhia tau tias muaj lwm cov ntsiab lus xws li S, uas tuaj yeem cuam tshuam nrog cov nroj tsuag rho tawm, siv. Tam sim no C: O piv thiab cov ntsiab lus hlau nyob rau hauv rGO / nZVI sib xyaw siv A. halimus yog qhov zoo dua li siv eucalyptus nplooj extract, raws li nws characterizes cov muaj pes tsawg leeg ntawm C (23.44 wt.%), O (68.29 wt.%) thiab Fe (8.27 wt.%). wt %) 25. Nataša et al., 2022 tau tshaj tawm cov ntsiab lus zoo sib xws ntawm nZVI synthesized los ntawm Oak thiab mulberry nplooj thiab paub tseeb tias pawg polyphenol thiab lwm cov molecules muaj nyob rau hauv nplooj extract yog lub luag hauj lwm rau cov txheej txheem txo.
Lub morphology ntawm nZVI synthesized nyob rau hauv cov nroj tsuag (Fig. S2A, B) yog spherical thiab ib nrab tsis xwm yeem, nrog ib tug nruab nrab particle loj ntawm 23.09 ± 3.54 nm, tab sis saw aggregates raug soj ntsuam vim van der Waals rog thiab ferromagnetism. Qhov no feem ntau granular thiab spherical particle zoo yog pom zoo nrog SEM cov txiaj ntsig. Ib qho kev soj ntsuam zoo sib xws tau pom los ntawm Abdelfatah li al. Nyob rau hauv 2021 thaum castor taum nplooj extract tau siv nyob rau hauv lub synthesis ntawm nZVI11. Ruelas tuberosa nplooj extract NPs siv los ua tus neeg sawv cev txo qis hauv nZVI kuj muaj cov duab kheej kheej nrog txoj kab uas hla ntawm 20 txog 40 nm26.
Hybrid rGO/nZVI composite TEM dluab (Fig. S2C-D) qhia tau hais tias rGO yog ib tug basal dav hlau nrog marginal folds thiab wrinkles muab ntau qhov chaw thauj khoom rau nZVI NPs; no lamellar morphology kuj lees paub qhov kev vam meej fabrication ntawm rGO. Tsis tas li ntawd, nZVI NPs muaj cov duab kheej kheej nrog qhov loj me ntawm 5.32 txog 27 nm thiab tau kos rau hauv rGO txheej nrog ib qho yuav luag tsis sib xws. Eucalyptus nplooj extract tau siv los ua ke Fe NPs / rGO; Cov txiaj ntsig TEM kuj tau lees paub tias cov wrinkles hauv rGO txheej tau txhim kho qhov tawg ntawm Fe NPs ntau dua li cov ntshiab Fe NPs thiab ua rau muaj kev cuam tshuam ntawm cov khoom sib xyaw. Cov txiaj ntsig zoo sib xws tau txais los ntawm Bagheri li al. 28 thaum cov khoom sib xyaw tau tsim los siv cov txheej txheem ultrasonic nrog qhov nruab nrab hlau nanoparticle loj ntawm kwv yees li 17.70 nm.
FTIR spectra ntawm A. halimus, nZVI, GO, rGO, thiab rGO/nZVI composites yog qhia nyob rau hauv daim duab. 3 A. Lub xub ntiag ntawm pawg ua haujlwm saum npoo ntawm nplooj ntawm A. halimus tshwm ntawm 3336 cm-1, uas sib haum rau polyphenols, thiab 1244 cm-1, uas sib haum rau carbonyl pawg tsim los ntawm cov protein. Lwm pawg xws li alkanes ntawm 2918 cm-1, alkenes ntawm 1647 cm-1 thiab CO-O-CO txuas ntxiv ntawm 1030 cm-1 kuj tau pom, qhia txog qhov muaj cov khoom cog uas ua raws li cov khoom sib khi thiab muaj lub luag haujlwm rau kev rov qab los. los ntawm Fe2+ rau Fe0 thiab mus rau rGO29. Feem ntau, nZVI spectra qhia tib qhov nqus siab tshaj li cov suab thaj iab, tab sis nrog txoj haujlwm hloov me ntsis. Ib pawg khaus tshwm sim ntawm 3244 cm-1 cuam tshuam nrog OH stretching vibrations (phenols), lub ncov ntawm 1615 sib raug rau C = C, thiab bands ntawm 1546 thiab 1011 cm-1 tshwm sim vim stretching ntawm C = O (polyphenols thiab flavonoids) , CN -groups ntawm aromatic amines thiab aliphatic amines kuj tau pom ntawm 1310 cm-1 thiab 1190 cm-1, ntsig txog 13. FTIR spectrum ntawm GO qhia tau hais tias muaj ntau pawg uas muaj cov pa oxygen, nrog rau cov alkoxy (CO) stretching band ntawm 1041 cm-1, epoxy (CO) stretching band ntawm 1291 cm-1, C = O stretch. ib pawg ntawm C = C stretching vibrations ntawm 1619 cm-1, ib tug band ntawm 1708 cm-1 thiab ib tug dav band ntawm OH pawg stretching vibrations ntawm 3384 cm-1 tshwm sim, uas yog paub tseeb hais tias los ntawm kev txhim kho Hummers txoj kev, uas ntse oxidizes lub graphite txheej txheem. Thaum muab piv rGO thiab rGO / nZVI composites nrog GO spectra, qhov kev siv ntawm qee cov pa oxygen, xws li OH ntawm 3270 cm-1, yog txo qis, thaum lwm tus, xws li C = O ntawm 1729 cm-1, yog tag nrho. txo. ploj mus, qhia txog kev tshem tawm cov pa oxygen-muaj cov pab pawg ua haujlwm hauv GO los ntawm A. halimus extract. Cov yam ntxwv tshiab ntse peaks ntawm rGO ntawm C = C nro tau pom nyob ib ncig ntawm 1560 thiab 1405 cm-1, uas lees paub qhov txo qis ntawm GO rau rGO. Kev hloov pauv ntawm 1043 txog 1015 cm-1 thiab los ntawm 982 txog 918 cm-1 tau pom, tejzaum nws suav nrog cov khoom cog31,32. Weng et al., 2018 kuj tau pom qhov txo qis ntawm cov pa oxygenated ua haujlwm hauv GO, lees paub qhov ua tiav ntawm rGO los ntawm bioreduction, txij li eucalyptus nplooj extracts, uas tau siv los ua ke txo cov hlau graphene oxide composites, pom ze dua FTIR spectra ntawm cov khoom cog. pab pawg ua haujlwm. 33.
A. FTIR spectrum of gallium, nZVI, rGO, GO, composite rGO/nZVI (A). Roentgenogrammy composites rGO, GO, nZVI thiab rGO/nZVI (B).
Kev tsim ntawm rGO / nZVI thiab nZVI cov khoom sib xyaw tau pom zoo los ntawm X-ray diffraction qauv (Fig. 3B). Lub siab siv Fe0 ncov tau pom ntawm 2˚44.5°, coj mus rau qhov ntsuas (110) (JCPDS no. 06–0696)11. Lwm lub ncov ntawm 35.1 ° ntawm lub dav hlau (311) yog ntaus nqi rau magnetite Fe3O4, 63.2 ° tej zaum yuav txuam nrog Miller Performance index ntawm (440) dav hlau vim muaj ϒ-FeOOH (JCPDS no. 17-0536)34. X-ray qauv ntawm GO qhia tau hais tias lub ncov ntse ntawm 2˚10.3° thiab lwm lub ncov ntawm 21.1°, qhia tias ua tiav exfoliation ntawm graphite thiab hais txog qhov muaj cov pa oxygen pawg ntawm GO35. Cov qauv sib xyaw ntawm rGO thiab rGO / nZVI tau sau tseg qhov ploj ntawm cov yam ntxwv GO peaks thiab tsim ntawm rGO peaks dav ntawm 2˚ 22.17 thiab 24.7 ° rau rGO thiab rGO / nZVI composites, ntsig txog, uas tau lees paub qhov ua tiav ntawm GO los ntawm cov nroj tsuag rho tawm. Txawm li cas los xij, hauv cov qauv sib xyaw rGO / nZVI, cov ncov ntxiv cuam tshuam nrog lub dav hlau lattice ntawm Fe0 (110) thiab bcc Fe0 (200) tau pom ntawm 44.9\(^\circ\) thiab 65.22\(^\circ\), feem. .
Lub peev xwm zeta yog qhov muaj peev xwm ntawm cov txheej txheem ionic txuas rau saum npoo ntawm cov khoom thiab cov tshuaj aqueous uas txiav txim siab cov khoom siv hluav taws xob electrostatic thiab ntsuas nws qhov ruaj khov37. Zeta muaj peev xwm tsom xam ntawm cov nroj tsuag-synthesized nZVI, GO, thiab rGO / nZVI composites qhia lawv cov kev ruaj ntseg vim muaj cov nqi tsis zoo ntawm -20.8, -22, thiab -27.4 mV, feem, ntawm lawv qhov chaw, raws li qhia hauv daim duab S1A- C. . Xws li cov txiaj ntsig tau zoo ib yam nrog ntau cov ntawv ceeb toom uas tau hais tias cov kev daws teeb meem uas muaj cov khoom siv zeta muaj peev xwm tsawg dua -25 mV feem ntau qhia tau tias muaj kev ruaj ntseg siab vim electrostatic repulsion ntawm cov khoom no. Kev sib xyaw ua ke ntawm rGO thiab nZVI tso cai rau cov khoom sib xyaw kom tau txais cov nqi tsis zoo thiab yog li muaj kev ruaj ntseg siab dua li GO lossis nZVI ib leeg. Yog li ntawd, qhov tshwm sim ntawm electrostatic repulsion yuav ua rau muaj kev ruaj ntseg rGO / nZVI39 composites. Qhov tsis zoo ntawm GO tso cai rau nws kom sib npaug ntawm qhov nruab nrab aqueous yam tsis muaj agglomeration, uas tsim kom muaj kev sib raug zoo nrog nZVI. Tus nqi tsis zoo yuav cuam tshuam nrog kev muaj cov pab pawg sib txawv hauv cov iab melon extract, uas tseem lees paub qhov kev cuam tshuam ntawm GO thiab hlau precursors thiab cov nroj tsuag extract los tsim rGO thiab nZVI, feem, thiab rGO / nZVI complex. Cov nroj tsuag cov tebchaw no tuaj yeem ua raws li cov neeg ua haujlwm capping, vim tias lawv tiv thaiv kev sib sau ua ke ntawm cov nanoparticles uas tshwm sim thiab yog li ua kom lawv ruaj khov 40.
Elemental muaj pes tsawg leeg thiab valence xeev ntawm cov nZVI thiab rGO/nZVI composites tau txiav txim los ntawm XPS (Fig. 4). Kev tshawb fawb XPS tag nrho tau pom tias rGO / nZVI sib xyaw yog tsim los ntawm cov ntsiab lus C, O, thiab Fe, raws li EDS mapping (Fig. 4F–H). Lub C1s spectrum muaj peb lub ncov ntawm 284.59 eV, 286.21 eV thiab 288.21 eV sawv cev rau CC, CO thiab C = O, feem. O1s spectrum tau muab faib ua peb lub ncov, suav nrog 531.17 eV, 532.97 eV, thiab 535.45 eV, uas tau muab rau O = CO, CO, thiab NO pawg, feem. Txawm li cas los xij, qhov siab tshaj ntawm 710.43, 714.57 thiab 724.79 eV xa mus rau Fe 2p3/2, Fe + 3 thiab Fe p1/2, feem. XPS spectra ntawm nZVI (Fig. 4C-E) pom qhov siab tshaj plaws rau cov ntsiab lus C, O, thiab Fe. Peaks ntawm 284.77, 286.25, thiab 287.62 eV paub meej tias muaj cov hlau-carbon alloys, raws li lawv xa mus rau CC, C-OH, thiab CO, feem. O1s spectrum sib raug mus rau peb lub ncov C-O / hlau carbonate (531.19 eV), hydroxyl radical (532.4 eV) thiab O-C = O (533.47 eV). Lub ncov ntawm 719.6 yog ntaus nqi rau Fe0, thaum FeOOH qhia peaks ntawm 717.3 thiab 723.7 eV, ntxiv rau, lub ncov ntawm 725.8 eV qhia tias muaj Fe2O342.43.
XPS cov kev tshawb fawb ntawm nZVI thiab rGO/nZVI composites, ntsig txog (A, B). Tag nrho cov spectra ntawm nZVI C1s (C), Fe2p (D), thiab O1s (E) thiab rGO/nZVI C1s (F), Fe2p (G), O1s (H) composite.
N2 adsorption/desorption isotherm (Fig. 5A, B) qhia tau hais tias cov nZVI thiab rGO/nZVI composites yog hom II. Tsis tas li ntawd, thaj chaw tshwj xeeb (SBET) ntawm nZVI tau nce los ntawm 47.4549 mus rau 152.52 m2 / g tom qab dig muag nrog rGO. Cov txiaj ntsig no tuaj yeem piav qhia los ntawm kev txo qis hauv cov khoom sib nqus ntawm nZVI tom qab rGO qhov muag tsis pom, yog li txo cov particle aggregation thiab ua rau thaj tsam ntawm cov khoom sib xyaw. Tsis tas li ntawd, raws li qhia hauv daim duab 5C, qhov pore ntim (8.94 nm) ntawm rGO / nZVI sib xyaw yog siab dua qhov qub nZVI (2.873 nm). Cov txiaj ntsig no tau pom zoo nrog El-Monaem li al. 45.
Txhawm rau ntsuas lub peev xwm adsorption kom tshem tawm DC ntawm rGO / nZVI cov khoom sib xyaw thiab cov thawj nZVI nyob ntawm qhov nce hauv thawj zaug concentration, kev sib piv tau ua los ntawm kev ntxiv ib koob tshuaj tas li ntawm txhua qhov adsorbent (0.05 g) rau DC ntawm ntau qhov pib concentrations. Tshawb nrhiav kev daws teeb meem [25]. -100 mg l-1] ntawm 25 ° C. Cov txiaj ntsig tau pom tias qhov kev tshem tawm tau zoo (94.6%) ntawm rGO / nZVI sib xyaw yog siab dua li ntawm thawj nZVI (90%) ntawm qhov qis dua (25 mg L-1). Txawm li cas los xij, thaum qhov pib concentration tau nce mus rau 100 mg L-1, qhov kev tshem tawm ntawm rGO / nZVI thiab niam txiv nZVI poob mus rau 70% thiab 65%, feem (Daim duab 6A), uas tej zaum yuav yog vim muaj tsawg dua qhov chaw ua haujlwm thiab degradation ntawm nZVI particle. Ntawm qhov tsis sib xws, rGO / nZVI tau pom qhov ua tau zoo dua ntawm DC tshem tawm, uas tej zaum yuav yog vim muaj kev sib koom ua ke ntawm rGO thiab nZVI, nyob rau hauv qhov chaw ruaj khov muaj rau adsorption ntau dua, thiab nyob rau hauv rooj plaub ntawm rGO / nZVI, ntau dua. DC tuaj yeem adsorbed dua li nZVI tsis zoo. Tsis tas li ntawd, hauv daim duab. 6B qhia tau hais tias lub peev xwm adsorption ntawm rGO / nZVI thiab nZVI composites tau nce los ntawm 9.4 mg / g mus rau 30 mg / g thiab 9 mg / g, feem, nrog kev nce hauv thawj zaug concentration ntawm 25-100 mg / L. 1.1-28.73 mg g-1. Yog li ntawd, DC tshem tawm tus nqi tau cuam tshuam tsis zoo nrog rau qhov pib DC concentration, uas yog vim muaj qhov tsawg ntawm cov tshuaj tiv thaiv cov chaw txhawb nqa los ntawm txhua qhov adsorbent rau adsorption thiab tshem tawm DC hauv kev daws teeb meem. Yog li, nws tuaj yeem txiav txim siab los ntawm cov txiaj ntsig no tias rGO / nZVI cov khoom sib xyaw muaj qhov ua tau zoo dua ntawm adsorption thiab txo qis, thiab rGO hauv cov ntsiab lus ntawm rGO / nZVI tuaj yeem siv tau ob qho tib si raws li adsorbent thiab cov khoom nqa khoom.
Kev tshem tawm thiab DC adsorption muaj peev xwm rau rGO / nZVI thiab nZVI sib xyaw yog (A, B) [Co = 25 mg l-1-100 mg l-1, T = 25 ° C, koob = 0.05 g], pH. ntawm adsorption muaj peev xwm thiab DC tshem tawm efficiency ntawm rGO/nZVI composites (C) [Co = 50 mg L–1, pH = 3–11, T = 25°C, koob = 0.05 g].
Kev daws pH yog qhov tseem ceeb hauv kev kawm txog cov txheej txheem adsorption, vim nws cuam tshuam rau qib ntawm ionization, speciation, thiab ionization ntawm cov adsorbent. Qhov kev sim tau ua tiav ntawm 25 ° C nrog rau qhov tshuaj adsorbent tas li (0.05 g) thiab thawj qhov concentration ntawm 50 mg L-1 hauv pH ntau (3-11). Raws li cov ntaub ntawv tshuaj xyuas 46, DC yog ib qho amphiphilic molecule nrog ntau pawg ionizable functional (phenols, amino pawg, cawv) ntawm ntau qib pH. Raws li qhov tshwm sim, ntau yam haujlwm ntawm DC thiab cov qauv muaj feem xyuam rau ntawm qhov chaw ntawm rGO / nZVI sib xyaw tuaj yeem cuam tshuam electrostatically thiab tej zaum yuav tshwm sim raws li cations, zwitterions, thiab anions, DC molecule muaj xws li cationic (DCH3 +) ntawm pH <3.3, zwitterionic (DCH20) 3.3 < pH < 7.7 thiab anionic (DCH− lossis DC2−) ntawm PH 7.7. Raws li qhov tshwm sim, ntau yam haujlwm ntawm DC thiab cov qauv muaj feem xyuam rau ntawm qhov chaw ntawm rGO / nZVI sib xyaw tuaj yeem cuam tshuam electrostatically thiab tej zaum yuav tshwm sim raws li cations, zwitterions, thiab anions, DC molecule muaj xws li cationic (DCH3 +) ntawm pH <3.3, zwitterionic (DCH20) 3.3 < pH < 7.7 thiab anionic (DCH- lossis DC2-) ntawm PH 7.7. В результате различные функции ДК и связанных с ними структур на поверхности композито rGO/nZVI вогрьсти татически и могут существовать в виде катионов, цвиттер-ионов и анионов, молекула ДК существует в винет ви 3 цвиттер- ионный (DCH20) 3,3 < pH < 7,7 thiab анионный (DCH- или DC2-) pH 7,7. Raws li qhov tshwm sim, ntau yam haujlwm ntawm DC thiab lwm yam qauv ntawm qhov chaw ntawm rGO / nZVI sib xyaw tuaj yeem cuam tshuam electrostatically thiab tuaj yeem muaj nyob rau hauv daim ntawv ntawm cations, zwitterions, thiab anions; DC molecule muaj nyob ua cation (DCH3+) ntawm pH <3.3; ionic (DCH20) 3.3 < pH < 7.7 thiab anionic (DCH- lossis DC2-) ntawm pH 7.7.因此，DC 的各种功能和rGO/nZVI 复合材料表面的相关结构可能会发生静电相互作用。两性离子和阴离子的形式存在，DC 分子在pH < 3.3 时以阳离子(DCH3+) 的形式存在，两性离子(DCH20) 3.3 < pH < 7.7 和阴离子(DCH-或DC2-) 在PH 7.7., DC 和 功能 和 和 和 和 复合 材料 表面 表面 可能 相关 可能 可能 可能 可能 发生 以 以 以以 阳离子阳离子 阳离子相互 阳离子相互 形式离子 形式离子相互,, DC 分子 在 在 在 在 在 在 在 在 阳离子 阳离子 阳离子 阳离子 阳离子阳离子 (dch3 +) 形式存在，两性离子(DCH20) 3.3 < pH < 7.7 和阴离子(DCH- 或DC2-) 在PH 7.7. Следовательно, различные функции ДК и родственных им структур на поверхности композита rGO/nZVI всупут ские взаимодействия и существовать в виде катионов, цвиттер-ионов и анионов, а молекулы ДК Дивкатерится 3, 3. Yog li ntawd, ntau yam kev ua haujlwm ntawm DC thiab cov qauv muaj feem xyuam rau ntawm qhov chaw ntawm rGO / nZVI sib xyaw tuaj yeem nkag mus rau hauv kev sib cuam tshuam electrostatic thiab muaj nyob rau hauv daim ntawv ntawm cations, zwitterions, thiab anions, thaum DC molecules yog cationic (DCH3 +) ntawm pH <3.3. Он существует в виде цвиттер-иона (DCH20) при 3,3 < pH < 7,7 и аниона (DCH- или DC2-) pH 7,7. Nws tshwm sim raws li zwitterion (DCH20) ntawm 3.3 < pH < 7.7 thiab anion (DCH- lossis DC2-) ntawm pH 7.7.Nrog nce pH ntawm 3 mus rau 7, lub peev xwm adsorption thiab efficiency ntawm DC tshem tawm tau nce los ntawm 11.2 mg / g (56%) mus rau 17 mg / g (85%) (Fig. 6C). Txawm li cas los xij, raws li pH nce mus rau 9 thiab 11, lub peev xwm adsorption thiab kev tshem tawm tau txo qis me ntsis, los ntawm 10.6 mg / g (53%) mus rau 6 mg / g (30%), feem. Nrog rau kev nce hauv pH ntawm 3 txog 7, DCs feem ntau muaj nyob rau hauv daim ntawv ntawm zwitterions, uas ua rau lawv yuav luag tsis-electrostatically nyiam los yog repulsed nrog rGO / nZVI composites, feem ntau los ntawm electrostatic kev sib cuam tshuam. Raws li pH nce siab tshaj 8.2, qhov saum npoo ntawm adsorbent tau raug them tsis zoo, yog li lub peev xwm adsorption poob qis thiab txo qis vim yog electrostatic repulsion ntawm qhov tsis zoo them doxycycline thiab nto ntawm cov adsorbent. Cov qauv no qhia tau hais tias DC adsorption ntawm rGO / nZVI composites yog pH nyob ntawm ntau, thiab cov txiaj ntsig kuj qhia tau tias rGO / nZVI cov khoom sib xyaw tsim nyog raws li adsorbents nyob rau hauv acidic thiab nruab nrab tej yam kev mob.
Cov nyhuv ntawm qhov kub ntawm qhov adsorption ntawm aqueous tov ntawm DC yog nqa tawm ntawm (25-55 ° C). Daim duab 7A qhia txog qhov tshwm sim ntawm qhov kub thiab txias ntawm qhov kev tshem tawm ntawm DC tshuaj tua kab mob ntawm rGO / nZVI, nws yog qhov tseeb tias qhov kev tshem tawm muaj peev xwm thiab adsorption muaj peev xwm nce los ntawm 83.44% thiab 13.9 mg / g rau 47% thiab 7.83 mg / g. , raws. Qhov kev txo qis no tuaj yeem yog vim qhov nce hauv thermal zog ntawm DC ions, uas ua rau desorption47.
Cov nyhuv ntawm qhov kub thiab txias ntawm kev tshem tawm Efficiency thiab Adsorption Peev Xwm ntawm CD ntawm rGO / nZVI Composites (A) [Co = 50 mg L–1, pH = 7, Dose = 0.05 g], Adsorbent Dose ntawm Kev tshem tawm Efficiency thiab tshem tawm cov txiaj ntsig ntawm CD Initial Concentration ntawm lub peev xwm adsorption thiab efficiency ntawm DC tshem tawm ntawm rGO/nSVI composite (B) [Co = 50 mg L–1, pH = 7, T = 25°C] (C, D) [Co = 25–100 mg L–1, pH = 7, T = 25°C, dose = 0.05 g].
Cov txiaj ntsig ntawm kev nce koob tshuaj ntawm cov khoom sib xyaw adsorbent rGO / nZVI los ntawm 0.01 g txog 0.07 g ntawm kev tshem tawm kev ua haujlwm thiab muaj peev xwm adsorption tau qhia hauv daim duab. 7B. Kev nce ntxiv ntawm cov tshuaj adsorbent ua rau txo qis ntawm qhov muaj peev xwm adsorption ntawm 33.43 mg / g rau 6.74 mg / g. Txawm li cas los xij, nrog kev nce ntxiv ntawm cov tshuaj adsorbent los ntawm 0.01 g txog 0.07 g, qhov kev tshem tawm tau nce los ntawm 66.8% mus rau 96%, uas, raws li, yuav cuam tshuam nrog kev nce ntawm cov chaw ua haujlwm ntawm nanocomposite nto.
Cov nyhuv ntawm thawj zaug concentration ntawm adsorption muaj peev xwm thiab tshem tawm efficiency [25-100 mg L-1, 25 ° C, pH 7, koob 0.05 g] tau kawm. Thaum thawj zaug concentration tau nce los ntawm 25 mg L-1 mus rau 100 mg L-1, qhov kev tshem tawm feem pua ntawm rGO / nZVI puas tau txo qis los ntawm 94.6% mus rau 65% (Daim duab 7C), tej zaum yog vim tsis muaj qhov xav tau active. qhov chaw. . Adsorbs loj concentration ntawm DC49. Ntawm qhov tod tes, raws li thawj zaug concentration nce, lub peev xwm adsorption kuj nce los ntawm 9.4 mg / g mus rau 30 mg / g kom txog thaum sib npaug (Fig. 7D). Cov tshuaj tiv thaiv tsis pom zoo no yog vim muaj kev nce hauv kev tsav tsheb nrog qhov pib DC concentration ntau dua li DC ion huab hwm coj hloov pauv mus txog qhov chaw 50 ntawm rGO / nZVI sib xyaw.
Lub sijhawm sib cuag thiab kev tshawb fawb kinetic tsom kom nkag siab lub sijhawm sib npaug ntawm adsorption. Ua ntej, tus nqi ntawm DC adsorbed hauv thawj 40 feeb ntawm lub sijhawm sib cuag yog kwv yees li ib nrab ntawm tag nrho cov nyiaj adsorbed tag nrho lub sijhawm (100 feeb). Thaum lub DC molecules nyob rau hauv cov tshuaj sib tsoo ua rau lawv tsiv mus nyob rau saum npoo ntawm rGO / nZVI sib xyaw ua rau muaj qhov cuam tshuam loj heev. Tom qab 40 feeb, DC adsorption nce zuj zus thiab maj mam kom txog thaum qhov sib npaug tau mus txog tom qab 60 min (Daim duab 7D). Txij li thaum tus nqi tsim nyog yog adsorbed hauv thawj 40 feeb, yuav muaj kev sib tsoo tsawg dua nrog DC molecules thiab tsawg dua qhov chaw ua haujlwm yuav muaj rau cov molecules uas tsis yog adsorbed. Yog li ntawd, tus nqi adsorption yuav txo tau 51.
Txhawm rau kom nkag siab zoo dua ntawm adsorption kinetics, kab phiaj xwm ntawm pseudo thawj qhov kev txiav txim (Daim duab 8A), pseudo thib ob xaj (Daim duab 8B), thiab Elovich (Fig. 8C) kinetic qauv tau siv. Los ntawm cov kev ntsuas tau los ntawm cov kev tshawb fawb kinetic (Table S1), nws pom tseeb tias tus qauv pseudosecond yog tus qauv zoo tshaj plaws rau kev piav qhia txog cov khoom adsorption kinetics, qhov twg tus nqi R2 tau teeb tsa siab dua li ntawm ob tus qauv. Kuj tseem muaj qhov zoo sib xws ntawm kev suav cov peev txheej adsorption (qe, cal). Qhov kev txiav txim thib ob thiab qhov kev sim qhov tseem ceeb (qe, exp.) yog cov pov thawj ntxiv tias qhov kev txiav txim thib ob yog tus qauv zoo dua li lwm cov qauv. Raws li tau pom nyob rau hauv Table 1, qhov tseem ceeb ntawm α (pib adsorption tus nqi) thiab β (desorption tas li) paub meej tias tus nqi adsorption siab dua tus nqi desorption, qhia tias DC nyhav rau adsorb zoo ntawm rGO / nZVI52 composite. .
Linear adsorption kinetic plots of pseudo-second order (A), pseudo-first order (B) and Elovich (C) [Co = 25–100 mg l–1, pH = 7, T = 25°C, dose = 0.05 g. ].
Kev tshawb fawb ntawm adsorption isotherms pab txiav txim siab lub peev xwm adsorption ntawm adsorbent (RGO / nRVI composite) ntawm ntau yam adsorbate concentrations (DC) thiab qhov system kub. Qhov siab tshaj plaws adsorption muaj peev xwm suav nrog Langmuir isotherm, uas qhia tias cov adsorption yog homogeneous thiab suav nrog kev tsim cov adsorbate monolayer rau saum npoo ntawm cov adsorbent yam tsis muaj kev cuam tshuam ntawm lawv53. Ob tug lwm cov qauv siv isotherm yog cov qauv Freundlich thiab Temkin. Txawm hais tias tus qauv Freundlich tsis siv los laij cov peev txheej adsorption, nws yuav pab kom nkag siab txog cov txheej txheem adsorption heterogeneous thiab qhov chaw ua haujlwm ntawm cov adsorbent muaj lub zog sib txawv, thaum tus qauv Temkin pab kom nkag siab txog lub cev thiab tshuaj lom neeg ntawm adsorption54.
Daim duab 9A-C qhia cov kab hauv kab ntawm Langmuir, Freindlich, thiab Temkin qauv, feem. R2 qhov tseem ceeb suav los ntawm Freundlich (Fig. 9A) thiab Langmuir (Fig. 9B) kab kab thiab nthuav tawm hauv Table 2 qhia tias DC adsorption ntawm rGO / nZVI composite ua raws li Freundlich (0.996) thiab Langmuir (0.988) isotherm qauv thiab Temkin (0.985). Qhov siab tshaj plaws adsorption muaj peev xwm (qmax), suav nrog Langmuir isotherm qauv, yog 31.61 mg g-1. Tsis tas li ntawd, tus nqi suav ntawm qhov tsis muaj qhov sib cais (RL) yog nruab nrab ntawm 0 thiab 1 (0.097), qhia txog cov txheej txheem adsorption zoo. Txwv tsis pub, qhov suav Freundlich tas li (n = 2.756) qhia qhov nyiam rau cov txheej txheem nqus dej no. Raws li cov qauv linear ntawm Temkin isotherm (Fig. 9C), qhov adsorption ntawm DC ntawm rGO/nZVI composite yog cov txheej txheem ntawm lub cev adsorption, txij li b yog ˂ 82 kJ mol-1 (0.408)55. Txawm hais tias lub cev adsorption feem ntau yog kho los ntawm cov tsis muaj zog van der Waals rog, ncaj qha tam sim no adsorption ntawm rGO / nZVI composites yuav tsum tsis muaj zog adsorption [56, 57].
Freundlich (A), Langmuir (B), thiab Temkin (C) linear adsorption isotherms [Co = 25–100 mg L–1, pH = 7, T = 25°C, koob = 0.05 g]. Plot of van't Hoff equation for DC adsorption by rGO/nZVI composites (D) [Co = 25–100 mg l-1, pH = 7, T = 25–55°C and dose = 0.05 g].
Txhawm rau ntsuas qhov cuam tshuam ntawm cov tshuaj tiv thaiv kub hloov ntawm DC tshem tawm los ntawm rGO / nZVI cov khoom sib xyaw, cov ntsuas kub tsis zoo xws li hloov pauv hloov pauv (ΔS), enthalpy hloov (ΔH), thiab lub zog hloov pauv dawb (ΔG) tau suav los ntawm kev sib npaug. 3 ib 458.
where \({K}_{e}\)=\(\frac{{C}_{Ae}}{{C}_{e}}\) – thermodynamic equilibrium constant, Ce and CAe – rGO in solution, Raws li /nZVI DC concentrations ntawm qhov chaw sib npaug. R thiab RT yog cov roj tsis tu ncua thiab adsorption kub, feem. Plotting ln Ke tiv thaiv 1/T muab txoj kab ncaj nraim (Daim duab 9D) los ntawm qhov uas ∆S thiab ∆H tuaj yeem txiav txim siab.
Qhov tsis zoo ΔH tus nqi qhia tias cov txheej txheem yog exothermic. Ntawm qhov tod tes, tus nqi ΔH yog nyob rau hauv lub cev adsorption txheej txheem. Qhov tsis zoo ΔG qhov tseem ceeb hauv Table 3 qhia tias adsorption yog ua tau thiab ua rau nws tus kheej. Cov txiaj ntsig tsis zoo ntawm ΔS qhia qhov kev txiav txim siab ntawm adsorbent molecules ntawm cov kua interface (Table 3).
Table 4 piv cov rGO / nZVI sib xyaw nrog lwm cov adsorbents qhia hauv kev tshawb fawb yav dhau los. Nws yog qhov tseeb tias VGO / nCVI composite muaj peev xwm adsorption siab thiab tej zaum yuav yog cov khoom cog lus rau kev tshem tawm DC tshuaj tua kab mob los ntawm dej. Tsis tas li ntawd, qhov adsorption ntawm rGO / nZVI composites yog cov txheej txheem ceev nrog lub sijhawm sib npaug ntawm 60 min. Cov khoom zoo adsorption ntawm rGO / nZVI sib xyaw tuaj yeem piav qhia los ntawm kev sib koom ua ke ntawm rGO thiab nZVI.
Daim duab 10A, B qhia txog lub laj thawj rau kev tshem tawm cov tshuaj tua kab mob DC los ntawm rGO/nZVI thiab nZVI complexes. Raws li cov txiaj ntsig ntawm kev sim ntawm cov nyhuv pH ntawm kev ua haujlwm ntawm DC adsorption, nrog rau kev nce hauv pH ntawm 3 txog 7, DC adsorption ntawm rGO / nZVI sib xyaw tsis tau tswj los ntawm electrostatic kev sib cuam tshuam, vim nws ua raws li zwitterion; Yog li ntawd, kev hloov pauv ntawm tus nqi pH tsis cuam tshuam rau cov txheej txheem adsorption. Tom qab ntawd, cov txheej txheem adsorption tuaj yeem tswj tau los ntawm kev sib cuam tshuam tsis yog electrostatic xws li hydrogen bonding, hydrophobic teebmeem, thiab π-π stacking kev sib cuam tshuam ntawm rGO / nZVI composite thiab DC66. Nws yog qhov paub zoo tias cov txheej txheem ntawm cov tshuaj tsw qab adsorbates ntawm qhov chaw ntawm txheej graphene tau piav qhia los ntawm π-π stacking kev sib cuam tshuam raws li lub ntsiab tsav tsheb. Cov khoom sib xyaw yog cov txheej txheem zoo ib yam li graphene nrog qhov nqus siab tshaj plaws ntawm 233 nm vim qhov hloov pauv π-π *. Raws li lub xub ntiag ntawm plaub lub nplhaib uas muaj ntxhiab nyob rau hauv cov qauv molecular ntawm DC adsorbate, peb xav tias muaj cov txheej txheem ntawm π-π-stacking kev sib cuam tshuam ntawm cov aromatic DC (π-electron acceptor) thiab thaj av nplua nuj nyob hauv π-electrons mus rau lub RGO nto. /nZVI composites. Tsis tas li ntawd, raws li qhia hauv daim duab. 10B, FTIR cov kev tshawb fawb tau ua los kawm txog kev sib cuam tshuam ntawm molecular ntawm rGO / nZVI cov khoom sib xyaw nrog DC, thiab FTIR spectra ntawm rGO / nZVI composites tom qab DC adsorption tau qhia hauv daim duab 10B. 10b ib. Lub ncov tshiab tau pom ntawm 2111 cm-1, uas sib haum rau lub moj khaum kev co ntawm C = C daim ntawv cog lus, uas qhia tau hais tias muaj cov koom haum organic ua haujlwm nyob rau saum npoo ntawm 67 rGO / nZVI. Lwm cov peaks hloov ntawm 1561 mus rau 1548 cm-1 thiab los ntawm 1399 mus rau 1360 cm-1, uas kuj tau lees paub tias π-π kev sib cuam tshuam ua lub luag haujlwm tseem ceeb hauv adsorption ntawm graphene thiab organic pollutants68,69. Tom qab DC adsorption, qhov kev siv ntawm qee cov pa oxygen, xws li OH, txo mus rau 3270 cm-1, uas qhia tias hydrogen bonding yog ib qho ntawm cov txheej txheem adsorption. Yog li, raws li cov txiaj ntsig, DC adsorption ntawm rGO / nZVI sib xyaw tshwm sim feem ntau yog vim π-π stacking kev sib cuam tshuam thiab H-bonds.
Rational mechanism ntawm adsorption ntawm DC tshuaj tua kab mob los ntawm rGO / nZVI thiab nZVI complexes (A). FTIR adsorption spectra ntawm DC ntawm rGO / nZVI thiab nZVI (B).
Kev siv zog ntawm nZVI ntawm 3244, 1615, 1546, thiab 1011 cm-1 nce ntxiv tom qab DC adsorption ntawm nZVI (Fig. 10B) piv rau nZVI, uas yuav tsum muaj feem xyuam nrog kev cuam tshuam nrog cov pab pawg ua haujlwm ntawm carboxylic acid. O pawg hauv DC. Txawm li cas los xij, qhov qis feem pua ntawm kev sib kis hauv tag nrho cov qhab nia tau pom tias tsis muaj kev hloov pauv tseem ceeb hauv cov adsorption efficiency ntawm phytosynthetic adsorbent (nZVI) piv rau nZVI ua ntej cov txheej txheem adsorption. Raws li qee qhov kev tshawb fawb DC tshem tawm nrog nZVI71, thaum nZVI reacts nrog H2O, electrons raug tso tawm thiab tom qab ntawd H + yog siv los tsim cov hydrogen txo qis heev. Thaum kawg, qee cov cationic tebchaw txais electrons los ntawm active hydrogen, uas ua rau -C = N thiab -C = C-, uas yog ntaus nqi mus rau lub splitting ntawm benzene nplhaib.
Post lub sij hawm: Nov-14-2022