Kev tshem tawm cov tshuaj tua kab mob doxycycline los ntawm dej los ntawm cov tshuaj ntsuab graphene oxide txo qis thiab nano-zero hlau complexes

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Hauv txoj haujlwm no, cov khoom sib xyaw rGO/nZVI tau tsim thawj zaug siv cov txheej txheem yooj yim thiab zoo rau ib puag ncig siv Sophora nplooj daj extract ua tus neeg sawv cev txo qis thiab stabilizer kom ua raws li cov ntsiab cai ntawm "ntsuab" chemistry, xws li kev tsim tshuaj lom neeg tsawg dua. Muaj ntau yam cuab yeej tau siv los lees paub qhov kev ua tiav ntawm cov khoom sib xyaw, xws li SEM, EDX, XPS, XRD, FTIR, thiab zeta muaj peev xwm, uas qhia txog kev tsim cov khoom sib xyaw ua tiav. Lub peev xwm tshem tawm ntawm cov khoom sib xyaw tshiab thiab nZVI ntshiab ntawm ntau qhov pib ntawm cov tshuaj tua kab mob doxycycline tau piv rau kev tshawb nrhiav qhov cuam tshuam synergistic ntawm rGO thiab nZVI. Nyob rau hauv cov xwm txheej tshem tawm ntawm 25mg L-1, 25 ° C thiab 0.05g, qhov kev tshem tawm adsorptive ntawm nZVI ntshiab yog 90%, thaum qhov kev tshem tawm adsorptive ntawm doxycycline los ntawm rGO/nZVI composite ncav cuag 94.6%, lees paub tias nZVI thiab rGO. Cov txheej txheem adsorption sib raug rau qhov kev txiav txim pseudo-second thiab yog qhov zoo sib xws nrog Freundlich qauv nrog lub peev xwm adsorption siab tshaj plaws ntawm 31.61 mg g-1 ntawm 25 ° C thiab pH 7. Ib txoj hauv kev tsim nyog rau kev tshem tawm DC tau raug pom zoo. Tsis tas li ntawd, kev siv dua ntawm rGO / nZVI composite yog 60% tom qab rau lub voj voog rov ua dua tshiab sib law liag.
Kev tsis txaus dej thiab kev ua qias tuaj tam sim no yog qhov kev hem thawj loj rau txhua lub tebchaws. Nyob rau xyoo tas los no, kev ua qias tuaj ntawm dej, tshwj xeeb tshaj yog kev ua qias tuaj ntawm tshuaj tua kab mob, tau nce ntxiv vim muaj kev tsim khoom thiab kev siv ntau ntxiv thaum muaj tus kab mob COVID-191,2,3. Yog li ntawd, kev tsim cov thev naus laus zis 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 tua kab mob semi-synthetic uas tiv taus los ntawm pawg tetracycline yog doxycycline (DC)4,5. Tau muaj kev tshaj tawm tias cov DC residues hauv cov dej hauv av thiab cov dej saum npoo av tsis tuaj yeem metabolized, tsuas yog 20-50% raug metabolized thiab cov seem raug tso tawm rau hauv ib puag ncig, ua rau muaj teeb meem loj rau ib puag ncig thiab kev noj qab haus huv6.
Kev raug rau DC ntawm qib qis tuaj yeem tua cov kab mob me me hauv dej photosynthetic, hem kev kis tus kab mob antimicrobial, thiab ua rau muaj kev tiv thaiv antimicrobial ntau ntxiv, yog li cov tshuaj lom no yuav tsum tau tshem tawm ntawm cov dej khib nyiab. Kev puas tsuaj ntuj tsim ntawm DC hauv dej yog ib qho txheej txheem qeeb heev. Cov txheej txheem physico-chemical xws li photolysis, biodegradation thiab adsorption tsuas yog tuaj yeem puas tsuaj ntawm cov concentration qis thiab ntawm tus nqi qis heev7,8. Txawm li cas los xij, txoj kev pheej yig tshaj plaws, yooj yim, tus phooj ywg ib puag ncig, yooj yim rau kev tswj hwm thiab ua haujlwm tau zoo yog adsorption9,10.
Nano xoom valent hlau (nZVI) yog ib yam khoom muaj zog heev uas tuaj yeem tshem tawm ntau yam tshuaj tua kab mob ntawm dej, suav nrog metronidazole, diazepam, ciprofloxacin, chloramphenicol, thiab tetracycline. Lub peev xwm no yog vim muaj cov khoom zoo kawg nkaus uas nZVI muaj, xws li kev ua haujlwm siab, thaj chaw loj, thiab ntau qhov chaw khi sab nraud11. Txawm li cas los xij, nZVI yooj yim sib sau ua ke hauv cov xov xwm aqueous vim yog van der Wells lub zog thiab cov khoom sib nqus siab, uas txo nws qhov ua tau zoo hauv kev tshem tawm cov pa phem vim yog kev tsim cov txheej oxide uas tiv thaiv kev ua haujlwm ntawm nZVI10,12. Kev sib sau ua ke ntawm cov khoom me me nZVI tuaj yeem txo qis los ntawm kev hloov kho lawv cov nplaim nrog surfactants thiab polymers lossis los ntawm kev sib xyaw nrog lwm cov 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 qhov ruaj khov hauv ib puag ncig13,14.
Graphene yog ib qho khoom siv carbon nano ob-seem uas muaj cov pa roj carbon sp2-hybridized uas teeb tsa hauv lub honeycomb lattice. Nws muaj thaj chaw loj, lub zog kho tshuab tseem ceeb, kev ua haujlwm electrocatalytic zoo heev, kev ua haujlwm thermal siab, kev txav mus los ntawm electron sai, thiab cov khoom siv thauj khoom tsim nyog los txhawb cov inorganic nanoparticles ntawm nws qhov chaw. Kev sib xyaw ua ke ntawm cov hlau nanoparticles thiab graphene tuaj yeem dhau qhov txiaj ntsig ntawm txhua yam khoom siv thiab, vim nws cov khoom siv lub cev thiab tshuaj zoo dua, muab kev faib tawm zoo tshaj plaws ntawm nanoparticles rau kev kho dej zoo dua15.
Cov tshuaj rho tawm ntawm cov nroj tsuag yog qhov kev xaiv zoo tshaj plaws rau cov tshuaj lom neeg txo cov tshuaj uas feem ntau siv rau hauv kev tsim cov graphene oxide txo qis (rGO) thiab nZVI vim tias lawv muaj, pheej yig, ib kauj ruam, muaj kev nyab xeeb rau ib puag ncig, thiab tuaj yeem siv ua cov neeg sawv cev txo qis. zoo li flavonoids thiab phenolic compounds kuj ua haujlwm ua tus stabilizer. Yog li ntawd, Atriplex halimus L. nplooj extract tau siv ua tus neeg sawv cev kho thiab kaw rau kev tsim cov rGO / nZVI composites hauv txoj kev tshawb fawb no. Atriplex halimus los ntawm tsev neeg Amaranthaceae yog ib tsob ntoo perennial uas nyiam nitrogen nrog ntau qhov chaw nyob deb16.
Raws li cov ntaub ntawv muaj, Atriplex halimus (A. halimus) thawj zaug siv los ua rGO/nZVI composites ua ib txoj kev tsim khoom pheej yig thiab zoo rau ib puag ncig. Yog li, lub hom phiaj ntawm txoj haujlwm no muaj plaub ntu: (1) phytosynthesis ntawm rGO/nZVI thiab niam txiv nZVI composites siv A. halimus aquatic leaf extract, (2) kev piav qhia ntawm phytosynthesized composites siv ntau txoj hauv kev los lees paub lawv txoj kev tsim khoom tiav, (3) kawm txog qhov cuam tshuam synergistic ntawm rGO thiab nZVI hauv kev nqus thiab tshem tawm cov organic contaminants ntawm doxycycline tshuaj tua kab mob nyob rau hauv ntau yam kev ntsuas tshuaj tiv thaiv, ua kom zoo dua cov xwm txheej ntawm cov txheej txheem adsorption, (3) tshawb xyuas cov ntaub ntawv sib xyaw hauv ntau yam kev kho mob txuas ntxiv tom qab lub voj voog ua tiav.
Doxycycline hydrochloride (DC, MM = 480.90, cov mis tshuaj C22H24N2O·HCl, 98%), hlau chloride hexahydrate (FeCl3.6H2O, 97%), hmoov graphite yuav los ntawm Sigma-Aldrich, Tebchaws Meskas. Sodium hydroxide (NaOH, 97%), ethanol (C2H5OH, 99.9%) thiab hydrochloric acid (HCl, 37%) tau yuav los ntawm Merck, Tebchaws Meskas. NaCl, KCl, CaCl2, MnCl2 thiab MgCl2 tau yuav los ntawm Tianjin Comio Chemical Reagent Co., Ltd. Tag nrho cov reagents yog cov khoom siv analytical purity siab. Dej ob zaug distilled tau siv los npaj tag nrho cov kua dej.
Cov qauv sawv cev ntawm A. halimus tau raug sau los ntawm lawv qhov chaw nyob hauv Nile Delta thiab thaj av raws ntug dej hiav txwv Mediterranean ntawm tebchaws Iziv. Cov khoom siv cog tau raug sau raws li cov lus qhia hauv tebchaws thiab thoob ntiaj teb17. Xibfwb Manal Fawzi tau txheeb xyuas cov qauv cog raws li Boulos18, thiab Lub Tsev Haujlwm Saib Xyuas Ib Puag Ncig ntawm Alexandria University tso cai rau kev sau cov hom nroj tsuag uas tau kawm rau lub hom phiaj kev tshawb fawb. Cov ntawv pov thawj qauv tau khaws cia ntawm Tanta University Herbarium (TANE), daim ntawv pov thawj naj npawb 14 122–14 127, ib lub tsev cog tshuaj pej xeem uas muab kev nkag mus rau cov ntaub ntawv tso cia. Tsis tas li ntawd, txhawm rau tshem tawm cov hmoov av lossis av, txiav cov nplooj ntawm cov nroj tsuag ua tej daim me me, yaug 3 zaug nrog cov kais dej thiab dej lim, thiab tom qab ntawd ziab ntawm 50 ° C. Cov nroj tsuag tau raug tsoo, 5 g ntawm cov hmoov zoo tau muab tso rau hauv 100 ml ntawm dej lim thiab do ntawm 70 ° C rau 20 feeb kom tau txais cov kua txiv. Cov kua txiv hmab txiv ntoo Bacillus nicotianae tau txais tau lim los ntawm daim ntawv lim Whatman thiab khaws cia rau hauv cov raj huv thiab sterilized ntawm 4 ° C rau kev siv ntxiv.
Raws li pom hauv Daim Duab 1, GO tau ua los ntawm hmoov graphite los ntawm txoj kev hloov kho Hummers. 10 mg ntawm hmoov GO tau muab faib rau hauv 50 ml ntawm dej deionized rau 30 feeb hauv qab sonication, thiab tom qab ntawd 0.9 g ntawm FeCl3 thiab 2.9 g ntawm NaAc tau sib xyaw rau 60 feeb. 20 ml ntawm atriplex nplooj extract tau ntxiv rau cov tshuaj sib xyaw nrog kev sib xyaw thiab tso rau ntawm 80 ° C rau 8 teev. Cov tshuaj dub tau raug lim. Cov nanocomposites npaj tau ntxuav nrog ethanol thiab dej bidistilled thiab tom qab ntawd ziab hauv qhov cub nqus tsev ntawm 50 ° C rau 12 teev.
Cov duab kos thiab cov duab digital ntawm kev tsim cov tshuaj ntsuab ntawm rGO / nZVI thiab nZVI complexes thiab tshem tawm cov tshuaj tua kab mob DC los ntawm cov dej tsis huv siv Atriplex halimus extract.
Raws li qhia hauv daim duab 1, 10 ml ntawm cov tshuaj hlau chloride uas muaj 0.05 M Fe3+ ions tau ntxiv rau 20 ml ntawm cov tshuaj nplooj iab rau 60 feeb nrog cua sov thiab do me ntsis, thiab tom qab ntawd cov tshuaj tau centrifuged ntawm 14,000 rpm (Hermle, 15,000 rpm) rau 15 feeb kom muab cov khoom dub, uas tom qab ntawd tau ntxuav 3 zaug nrog ethanol thiab dej distilled thiab tom qab ntawd ziab hauv lub qhov cub nqus tsev ntawm 60° C. ib hmos.
Cov khoom sib xyaw ua ke rGO/nZVI thiab nZVI uas tsim los ntawm cov nroj tsuag tau piav qhia los ntawm UV-pom spectroscopy (T70/T80 series UV/Vis spectrophotometers, PG Instruments Ltd, UK) hauv qhov ntau ntawm 200-800 nm. Txhawm rau tshuaj xyuas qhov chaw thiab qhov loj me ntawm cov khoom sib xyaw rGO/nZVI thiab nZVI, TEM spectroscopy (JOEL, JEM-2100F, Nyiv Pooj, qhov hluav taws xob nrawm 200 kV) tau siv. Txhawm rau soj ntsuam cov pab pawg ua haujlwm uas tuaj yeem koom nrog cov nroj tsuag rho tawm uas yog lub luag haujlwm rau kev rov qab thiab kev ruaj khov, FT-IR spectroscopy tau ua tiav (JASCO spectrometer hauv qhov ntau ntawm 4000-600 cm-1). Tsis tas li ntawd, lub zeta potential analyzer (Zetasizer Nano ZS Malvern) tau siv los kawm txog qhov them ntawm cov nanomaterials uas tau tsim los. Rau kev ntsuas X-ray diffraction ntawm cov hmoov nanomaterials, lub X-ray diffractometer (X'PERT PRO, Netherlands) tau siv, ua haujlwm ntawm tam sim no (40 mA), voltage (45 kV) hauv 2θ ntau ntawm 20 ° txog 80 ° thiab CuKa1 hluav taws xob (\(\lambda =\ ) 1.54056 Ao). Lub zog dispersive X-ray spectrometer (EDX) (qauv JEOL JSM-IT100) yog lub luag haujlwm rau kev kawm cov khoom sib xyaw thaum sau Al K-α monochromatic X-rays los ntawm -10 txog 1350 eV ntawm XPS, qhov loj me 400 μm K-ALPHA (Thermo Fisher Scientific, USA) lub zog kis ntawm tag nrho spectrum yog 200 eV thiab qhov spectrum nqaim yog 50 eV. Cov qauv hmoov raug nias rau ntawm lub thawv qauv, uas tau muab tso rau hauv lub tshuab nqus tsev. Lub C1s spectrum tau siv ua qhov siv ntawm 284.58 eV los txiav txim siab lub zog khi.
Cov kev sim adsorption tau ua los sim qhov ua tau zoo ntawm cov synthesized rGO/nZVI nanocomposites hauv kev tshem tawm doxycycline (DC) ntawm cov kua dej. Cov kev sim adsorption tau ua nyob rau hauv 25 ml Erlenmeyer flasks ntawm qhov ceev co ntawm 200 rpm ntawm lub orbital shaker (Stuart, Orbital Shaker/SSL1) ntawm 298 K. Los ntawm kev diluting DC stock solution (1000 ppm) nrog bidistilled dej. Txhawm rau ntsuas qhov cuam tshuam ntawm rGO/nSVI koob tshuaj ntawm qhov ua tau zoo adsorption, nanocomposites ntawm qhov hnyav sib txawv (0.01–0.07 g) tau ntxiv rau 20 ml ntawm DC kua. Txhawm rau kawm txog kinetics thiab adsorption isotherms, 0.05 g ntawm adsorbent tau immersed nyob rau hauv cov kua dej ntawm CD nrog qhov concentration pib (25–100 mg L–1). Cov nyhuv ntawm pH rau kev tshem tawm DC tau kawm ntawm pH (3–11) thiab qhov pib concentration ntawm 50 mg L-1 ntawm 25 ° C. Kho qhov pH ntawm lub cev los ntawm kev ntxiv me ntsis ntawm HCl lossis NaOH kua (Crison pH meter, pH meter, pH 25). Tsis tas li ntawd, qhov cuam tshuam ntawm qhov kub ntawm cov tshuaj tiv thaiv rau kev sim adsorption hauv qhov ntau ntawm 25-55 ° C tau tshawb nrhiav. Cov nyhuv ntawm ionic lub zog rau cov txheej txheem adsorption tau kawm los ntawm kev ntxiv ntau yam concentration 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 qho adsorbent koob tshuaj ntawm 0.05 g. Qhov adsorption ntawm cov DC uas tsis adsorbed tau ntsuas siv lub dual beam UV-Vis spectrophotometer (T70/T80 series, PG Instruments Ltd, UK) nruab nrog 1.0 cm txoj kev ntev quartz cuvettes ntawm qhov siab tshaj plaws wavelengths (λmax) ntawm 270 thiab 350 nm. Qhov feem pua ​​​​​​ntawm kev tshem tawm ntawm DC tshuaj tua kab mob (R%; Eq. 1) thiab qhov adsorption ntawm DC, qt, Eq. 2 (mg / g) tau ntsuas siv cov qauv hauv qab no.
qhov twg %R yog lub peev xwm tshem tawm DC (%), Co yog qhov pib DC concentration thaum lub sijhawm 0, thiab C yog qhov DC concentration thaum lub sijhawm t, raws li (mg L-1).
qhov twg qe yog qhov ntau ntawm DC adsorbed ib chav tsev ntawm cov adsorbent (mg g-1), Co thiab Ce yog cov concentration ntawm xoom lub sijhawm thiab ntawm qhov sib npaug, feem (mg l-1), V yog qhov ntim kua (l), thiab m yog cov tshuaj adsorption mass reagent (g).
Cov duab SEM (Daim duab 2A-C) qhia txog cov qauv lamellar ntawm rGO/nZVI composite nrog cov hlau spherical nanoparticles uas sib cais sib npaug ntawm nws qhov chaw, qhia txog kev txuas nZVI NPs rau ntawm qhov chaw rGO. Tsis tas li ntawd, muaj qee qhov wrinkles hauv nplooj rGO, lees paub qhov kev tshem tawm ntawm cov pab pawg uas muaj oxygen tib lub sijhawm nrog kev kho dua tshiab ntawm A. halimus GO. Cov wrinkles loj no ua haujlwm ua qhov chaw rau kev thauj khoom ntawm cov hlau NPs. Cov duab nZVI (Daim duab 2D-F) qhia tau hais tias cov hlau spherical NPs tau tawg ua ntau heev thiab tsis sib sau ua ke, uas yog vim qhov xwm txheej ntawm cov khoom xyaw botanical ntawm cov nroj tsuag extract. Qhov loj me ntawm cov khoom sib txawv hauv 15-26 nm. Txawm li cas los xij, qee thaj chaw muaj cov qauv mesoporous nrog cov qauv ntawm cov bulges thiab cavities, uas tuaj yeem muab lub peev xwm adsorption zoo ntawm nZVI, vim tias lawv tuaj yeem ua rau muaj peev xwm ntes DC molecules ntawm qhov chaw ntawm nZVI. Thaum Rosa Damascus extract siv rau kev tsim cov nZVI, cov NPs tau txais tsis sib xws, nrog cov voids thiab cov duab sib txawv, uas txo lawv cov kev ua haujlwm hauv Cr (VI) adsorption thiab ua rau lub sijhawm teb ntau dua 23. Cov txiaj ntsig yog sib xws nrog nZVI synthesized los ntawm cov ntoo qhib thiab nplooj mulberry, uas feem ntau yog cov nanoparticles kheej kheej nrog ntau qhov ntau thiab tsawg nanometer yam tsis muaj kev sib sau ua ke.
Cov duab SEM ntawm rGO/nZVI (AC), nZVI (D, E) composites thiab EDX cov qauv ntawm nZVI/rGO (G) thiab nZVI (H) composites.
Cov khoom sib xyaw ua ke ntawm cov nroj tsuag-synthesized rGO/nZVI thiab nZVI composites tau kawm siv EDX (Daim Duab 2G, H). Cov kev tshawb fawb qhia tau tias nZVI yog tsim los ntawm carbon (38.29% los ntawm qhov hnyav), oxygen (47.41% los ntawm qhov hnyav) thiab hlau (11.84% los ntawm qhov hnyav), tab sis lwm yam khoom xws li phosphorus24 kuj muaj, uas tuaj yeem tau txais los ntawm cov nroj tsuag extracts. Tsis tas li ntawd, feem pua ​​​​​​ntawm carbon thiab oxygen yog vim muaj phytochemicals los ntawm cov nroj tsuag extracts hauv cov qauv nZVI hauv av. Cov khoom no tau faib sib npaug ntawm rGO tab sis nyob rau hauv cov piv sib txawv: C (39.16 wt%), O (46.98 wt%) thiab Fe (10.99 wt%), EDX rGO/nZVI kuj qhia tau tias muaj lwm yam khoom xws li S, uas tuaj yeem cuam tshuam nrog cov nroj tsuag extracts, siv. Qhov piv ntawm C:O tam sim no thiab cov hlau hauv rGO/nZVI sib xyaw siv A. halimus zoo dua li siv cov nplooj eucalyptus extract, vim nws piav qhia txog cov khoom sib xyaw ntawm C (23.44 wt.%), O (68.29 wt.%) thiab Fe (8.27 wt.%). wt%) 25. Nataša et al., 2022 tau tshaj tawm cov khoom sib xyaw zoo sib xws ntawm nZVI synthesized los ntawm nplooj ntoo qhib thiab nplooj mulberry thiab lees paub tias cov pab pawg polyphenol thiab lwm cov molecules uas muaj nyob hauv cov nplooj extract yog lub luag haujlwm rau cov txheej txheem txo qis.
Tus qauv ntawm nZVI uas tau tsim los ntawm cov nroj tsuag (Daim Duab S2A, B) yog kheej kheej thiab qee qhov tsis sib xws, nrog rau qhov nruab nrab ntawm cov khoom me me ntawm 23.09 ± 3.54 nm, txawm li cas los xij cov saw hlau tau pom vim yog van der Waals lub zog thiab ferromagnetism. Cov duab ntawm cov khoom me me thiab kheej kheej no feem ntau yog qhov sib haum xeeb zoo nrog cov txiaj ntsig SEM. Ib qho kev soj ntsuam zoo sib xws tau pom los ntawm Abdelfatah et al. hauv xyoo 2021 thaum cov kua txiv hmab txiv ntoo castor tau siv hauv kev tsim cov nZVI11. Ruelas tuberosa nplooj extract NPs siv ua tus neeg sawv cev txo qis hauv nZVI kuj muaj cov duab kheej kheej nrog lub cheeb ntawm 20 txog 40 nm26.
Cov duab sib xyaw ua ke rGO/nZVI sib xyaw TEM (Daim duab S2C-D) qhia tau hais tias rGO yog lub dav hlau basal nrog cov kab txaij thiab cov kab txaij muab ntau qhov chaw thauj khoom rau nZVI NPs; qhov lamellar morphology no kuj lees paub qhov ua tiav ntawm rGO. Tsis tas li ntawd, nZVI NPs muaj lub duab kheej kheej nrog cov qhov loj me ntawm 5.32 txog 27 nm thiab tau muab tso rau hauv rGO txheej nrog qhov sib txawv yuav luag sib xws. Eucalyptus nplooj extract tau siv los ua ke Fe NPs/rGO; Cov txiaj ntsig TEM kuj lees paub tias cov kab txaij hauv rGO txheej tau txhim kho qhov kev sib txawv ntawm Fe NPs ntau dua li Fe NPs ntshiab thiab ua rau muaj kev cuam tshuam ntawm cov khoom sib xyaw. Cov txiaj ntsig zoo sib xws tau txais los ntawm Bagheri et al. 28 thaum cov khoom sib xyaw tau tsim los ntawm kev siv cov txheej txheem ultrasonic nrog qhov nruab nrab hlau nanoparticle loj ntawm kwv yees li 17.70 nm.
Cov FTIR spectra ntawm A. halimus, nZVI, GO, rGO, thiab rGO/nZVI composites tau qhia nyob rau hauv Figs. 3A. Qhov muaj cov pab pawg ua haujlwm ntawm qhov chaw hauv nplooj ntawm A. halimus tshwm sim ntawm 3336 cm-1, uas sib raug rau polyphenols, thiab 1244 cm-1, uas sib raug rau cov pab pawg carbonyl tsim los ntawm cov protein. Lwm pab pawg xws li alkanes ntawm 2918 cm-1, alkenes ntawm 1647 cm-1 thiab CO-O-CO extensions ntawm 1030 cm-1 kuj tau pom, qhia txog qhov muaj cov khoom cog uas ua haujlwm ua cov neeg sawv cev thiab yog lub luag haujlwm rau kev rov qab los ntawm Fe2 + ​​rau Fe0 thiab GO rau rGO29. Feem ntau, cov nZVI spectra qhia tib lub ncov nqus zoo li cov suab thaj iab, tab sis nrog qhov chaw hloov pauv me ntsis. Ib txoj kab sib zog tshwm sim ntawm 3244 cm-1 cuam tshuam nrog OH ncab kev co (phenols), lub ncov ntawm 1615 sib raug rau C = C, thiab cov kab ntawm 1546 thiab 1011 cm-1 tshwm sim vim yog ncab ntawm C = O (polyphenols thiab flavonoids), CN-pawg ntawm aromatic amines thiab aliphatic amines kuj tau pom ntawm 1310 cm-1 thiab 1190 cm-1, feem13. Lub FTIR spectrum ntawm GO qhia txog qhov muaj ntau pawg oxygen-muaj zog, suav nrog alkoxy (CO) ncab band ntawm 1041 cm-1, epoxy (CO) ncab band ntawm 1291 cm-1, C = O ncab. ib txoj kab ntawm C = C ncab kev co ntawm 1619 cm-1, ib txoj kab ntawm 1708 cm-1 thiab ib txoj kab dav ntawm OH pawg ncab kev co ntawm 3384 cm-1 tau tshwm sim, uas tau lees paub los ntawm txoj kev Hummers zoo dua, uas ua tiav oxidizes cov txheej txheem graphite. Thaum piv rGO thiab rGO / nZVI composites nrog GO spectra, qhov muaj zog ntawm qee pawg uas muaj oxygen, xws li OH ntawm 3270 cm-1, raug txo qis heev, thaum lwm tus, xws li C = O ntawm 1729 cm-1, raug txo qis tag nrho. ploj mus, qhia txog kev tshem tawm cov pab pawg ua haujlwm uas muaj oxygen hauv GO los ntawm A. halimus extract. Cov ncov tshiab ntse ntawm rGO ntawm C = C nro tau pom nyob ib puag ncig 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 ntawm 982 txog 918 cm-1 tau pom, tej zaum vim muaj cov khoom siv cog31,32. Weng et al., 2018 kuj tau pom qhov txo qis ntawm cov pab pawg ua haujlwm oxygenated hauv GO, lees paub qhov kev tsim rGO zoo los ntawm bioreduction, txij li cov nplooj eucalyptus extracts, uas tau siv los ua cov hlau graphene oxide composites txo qis, tau qhia txog FTIR spectra ze dua ntawm cov pab pawg ua haujlwm cog.33.
A. FTIR spectrum ntawm gallium, nZVI, rGO, GO, composite rGO/nZVI (A). Roentgenogrammy composites rGO, GO, nZVI thiab rGO/nZVI (B).
Qhov kev tsim ntawm rGO/nZVI thiab nZVI composites tau lees paub los ntawm cov qauv X-ray diffraction (Daim Duab 3B). Ib qho siab Fe0 ncov tau pom ntawm 2Ƭ 44.5°, sib raug rau cov ntsuas (110) (JCPDS no. 06–0696)11. Lwm qhov ncov ntawm 35.1° ntawm (311) dav hlau yog vim magnetite Fe3O4, 63.2° tej zaum yuav cuam tshuam nrog Miller index ntawm (440) dav hlau vim muaj ϒ-FeOOH (JCPDS no. 17-0536)34. Tus qauv X-ray ntawm GO qhia txog qhov siab tshaj plaws ntawm 2Ƭ 10.3° thiab lwm qhov ncov ntawm 21.1°, qhia txog kev tawm ntawm graphite tag nrho thiab qhia txog qhov muaj cov pab pawg oxygen ntawm qhov chaw ntawm GO35. Cov qauv sib xyaw ua ke ntawm rGO thiab rGO/nZVI tau kaw qhov ploj ntawm cov yam ntxwv GO peaks thiab kev tsim cov dav rGO peaks ntawm 2Ư 22.17 thiab 24.7° rau rGO thiab rGO/nZVI composites, feem, uas tau lees paub qhov kev rov qab zoo ntawm GO los ntawm cov nroj tsuag extracts. Txawm li cas los xij, hauv cov qauv sib xyaw ua ke rGO/nZVI, cov peaks 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 lub peev xwm ntawm ib txheej ionic txuas rau ntawm qhov chaw ntawm ib qho khoom me me thiab cov kua dej uas txiav txim siab cov khoom siv electrostatic ntawm cov khoom siv thiab ntsuas nws qhov ruaj khov37. Kev tshuaj xyuas lub peev xwm Zeta ntawm cov nroj tsuag-synthesized nZVI, GO, thiab rGO/nZVI composites tau qhia lawv qhov ruaj khov vim muaj cov nqi tsis zoo ntawm -20.8, -22, thiab -27.4 mV, feem, ntawm lawv qhov chaw, raws li pom hauv Daim Duab S1A-C. . Cov txiaj ntsig zoo li no yog sib xws nrog ntau daim ntawv tshaj tawm uas hais tias cov tshuaj muaj cov khoom me me nrog cov nqi zeta muaj peev xwm tsawg dua -25 mV feem ntau qhia txog qib siab ntawm kev ruaj khov vim yog electrostatic repulsion ntawm cov khoom me me no. Kev sib xyaw ua ke ntawm rGO thiab nZVI tso cai rau cov khoom sib xyaw kom tau txais cov nqi tsis zoo ntau dua thiab yog li muaj kev ruaj khov siab dua li GO lossis nZVI ib leeg. Yog li ntawd, qhov tshwm sim ntawm electrostatic repulsion yuav ua rau muaj kev tsim cov khoom sib xyaw rGO/nZVI39 ruaj khov. Qhov chaw tsis zoo ntawm GO tso cai rau nws kom sib npaug hauv cov dej nruab nrab yam tsis muaj agglomeration, uas tsim cov xwm txheej zoo rau kev sib cuam tshuam nrog nZVI. Qhov them tsis zoo yuav cuam tshuam nrog qhov muaj cov pab pawg ua haujlwm sib txawv hauv cov kua txiv qaub iab iab, uas kuj lees paub qhov kev sib cuam tshuam ntawm GO thiab cov hlau ua ntej thiab cov nroj tsuag extract los tsim rGO thiab nZVI, feem, thiab rGO / nZVI complex. Cov tshuaj cog no kuj tuaj yeem ua haujlwm ua cov neeg sawv cev capping, vim lawv tiv thaiv kev sib sau ua ke ntawm cov nanoparticles thiab yog li ua rau lawv ruaj khov40.
Cov khoom sib xyaw ua ke thiab cov xeev valence ntawm nZVI thiab rGO/nZVI composites tau txiav txim siab los ntawm XPS (Daim Duab 4). Kev tshawb fawb XPS tag nrho qhia tau hais tias rGO/nZVI composite feem ntau yog tsim los ntawm cov ntsiab lus C, O, thiab Fe, sib xws nrog EDS mapping (Daim Duab 4F-H). Lub spectrum C1s muaj peb lub ncov ntawm 284.59 eV, 286.21 eV thiab 288.21 eV sawv cev rau CC, CO thiab C = O, feem. Lub spectrum O1s tau muab faib ua peb lub ncov, suav nrog 531.17 eV, 532.97 eV, thiab 535.45 eV, uas tau muab faib rau O = CO, CO, thiab NO pawg, feem. Txawm li cas los xij, cov ncov ntawm 710.43, 714.57 thiab 724.79 eV xa mus rau Fe 2p3/2, Fe+3 thiab Fe p1/2, feem. Cov XPS spectra ntawm nZVI (Daim Duab 4C-E) qhia cov ncov rau cov ntsiab lus C, O, thiab Fe. Cov ncov ntawm 284.77, 286.25, thiab 287.62 eV lees paub qhov muaj cov hlau-carbon alloys, raws li lawv xa mus rau CC, C-OH, thiab CO, raws li. Cov O1s spectrum sib raug rau peb lub ncov C-O/iron carbonate (531.19 eV), hydroxyl radical (532.4 eV) thiab O-C=O (533.47 eV). Lub ncov ntawm 719.6 yog muab rau Fe0, thaum FeOOH qhia cov ncov ntawm 717.3 thiab 723.7 eV, ntxiv rau, lub ncov ntawm 725.8 eV qhia qhov muaj Fe2O342.43.
Cov kev tshawb fawb XPS ntawm nZVI thiab rGO/nZVI composites, raws li (A, B). Cov spectra tag nrho ntawm nZVI C1s (C), Fe2p (D), thiab O1s (E) thiab rGO/nZVI C1s (F), Fe2p (G), O1s (H) composite.
Tus N2 adsorption/desorption isotherm (Daim Duab 5A, B) qhia tau hais tias cov nZVI thiab rGO/nZVI composites koom nrog hom II. Tsis tas li ntawd, thaj chaw tshwj xeeb (SBET) ntawm nZVI tau nce ntxiv los ntawm 47.4549 mus rau 152.52 m2/g tom qab blinding nrog rGO. Qhov tshwm sim no tuaj yeem piav qhia los ntawm kev txo qis hauv cov khoom sib nqus ntawm nZVI tom qab rGO blinding, yog li txo cov khoom sib sau ua ke thiab nce thaj chaw ntawm cov composites. Tsis tas li ntawd, raws li pom hauv Daim Duab 5C, qhov ntim pore (8.94 nm) ntawm rGO/nZVI composite siab dua li ntawm nZVI thawj (2.873 nm). Qhov tshwm sim no yog nyob rau hauv kev pom zoo nrog El-Monaem et al. 45.
Txhawm rau soj ntsuam qhov muaj peev xwm adsorption kom tshem tawm DC ntawm cov rGO/nZVI composites thiab nZVI thawj zaug nyob ntawm qhov nce ntawm qhov concentration pib, kev sib piv tau ua los ntawm kev ntxiv cov koob tshuaj tas li ntawm txhua tus adsorbent (0.05 g) rau DC ntawm ntau qhov concentration pib. Kev tshuaj xyuas cov tshuaj [25]. –100 mg l–1] ntawm 25°C. Cov txiaj ntsig tau qhia tias qhov kev ua haujlwm tshem tawm (94.6%) ntawm rGO/nZVI composite siab dua li ntawm nZVI thawj zaug (90%) ntawm qhov concentration qis dua (25 mg L-1). Txawm li cas los xij, thaum qhov concentration pib tau nce mus rau 100 mg L-1, qhov kev ua haujlwm tshem tawm ntawm rGO/nZVI thiab niam txiv nZVI poob qis mus rau 70% thiab 65%, feem (Daim Duab 6A), uas tej zaum yuav yog vim muaj tsawg dua qhov chaw ua haujlwm thiab kev puas tsuaj ntawm nZVI cov khoom me me. Ntawm qhov tsis sib xws, rGO/nZVI tau qhia txog kev ua haujlwm zoo dua ntawm DC tshem tawm, uas tej zaum yuav yog vim muaj kev sib koom ua ke ntawm rGO thiab nZVI, uas cov chaw ruaj khov muaj rau kev nqus tau ntau dua, thiab hauv rooj plaub ntawm rGO/nZVI, ntau DC tuaj yeem nqus tau ntau dua li nZVI tsis hloov pauv. Tsis tas li ntawd, hauv daim duab 6B qhia tau tias lub peev xwm nqus ntawm rGO/nZVI thiab nZVI composites tau nce ntxiv los ntawm 9.4 mg/g mus rau 30 mg/g thiab 9 mg/g, feem, nrog rau kev nce hauv qhov concentration pib los ntawm 25–100 mg/L. -1.1 txog 28.73 mg g-1. Yog li ntawd, tus nqi tshem tawm DC tau cuam tshuam tsis zoo nrog qhov concentration pib DC, uas yog vim muaj tus lej tsawg ntawm cov chaw teb uas txhawb nqa los ntawm txhua tus adsorbent rau kev nqus thiab tshem tawm DC hauv cov kua. Yog li, nws tuaj yeem xaus lus los ntawm cov txiaj ntsig no tias cov rGO / nZVI composites muaj kev ua haujlwm zoo dua ntawm kev nqus thiab txo qis, thiab rGO hauv cov khoom sib xyaw ntawm rGO / nZVI tuaj yeem siv ob qho tib si ua cov adsorbent thiab ua cov khoom siv nqa khoom.
Qhov kev ua haujlwm tshem tawm thiab DC adsorption peev xwm rau rGO/nZVI thiab nZVI composite yog (A, B) [Co = 25 mg l-1–100 mg l-1, T = 25 °C, koob tshuaj = 0.05 g], pH. ntawm lub peev xwm adsorption thiab DC tshem tawm kev ua haujlwm ntawm rGO/nZVI composites (C) [Co = 50 mg L–1, pH = 3–11, T = 25 °C, koob tshuaj = 0.05 g].
pH ntawm cov kua yog ib qho 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 cov koob tshuaj adsorbent tas li (0.05 g) thiab qhov concentration pib ntawm 50 mg L-1 hauv pH ntau (3–11). Raws li kev tshuaj xyuas cov ntaub ntawv sau46, DC yog ib qho molecule amphiphilic nrog ntau pawg ionizable functional (phenols, amino pawg, cawv) ntawm ntau qib pH. Yog li ntawd, ntau yam haujlwm ntawm DC thiab cov qauv cuam tshuam ntawm qhov chaw ntawm rGO / nZVI composite yuav cuam tshuam electrostatically thiab tej zaum yuav muaj nyob ua cations, zwitterions, thiab anions, lub DC molecule muaj nyob ua cationic (DCH3 +) ntawm pH < 3.3, zwitterionic (DCH20) 3.3 < pH < 7.7 thiab anionic (DCH− lossis DC2−) ntawm PH 7.7. Yog li ntawd, ntau yam haujlwm ntawm DC thiab cov qauv cuam tshuam ntawm qhov chaw ntawm rGO / nZVI composite yuav cuam tshuam electrostatically thiab tej zaum yuav muaj nyob ua cations, zwitterions, thiab anions, lub DC molecule muaj nyob ua 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 композита rGO/nZVI возьтет электростатически и могут существовать в виде катионов, цвиттер-ионов и анионов, молекула ДК сувитес т вуектростатически (DCH3+) при рН < 3,3, цвиттер-ионный (DCH20) 3,3 < pH < 7,7 и анионный (DCH- или DC2-) при pH 7,7. Yog li ntawd, ntau yam haujlwm ntawm DC thiab cov qauv cuam tshuam ntawm qhov chaw ntawm rGO / nZVI composite tuaj yeem sib cuam tshuam electrostatically thiab tuaj yeem muaj nyob rau hauv daim ntawv ntawm cations, zwitterions, thiab anions; lub DC molecule muaj nyob ua ib qho 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，并可能以阳离子、两性离子和阴离子的形式存在，DC 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.因此，dc的种功能和和和和复合材料表面的相关结构相可能縔面的相关结构 盵能縔 发并可能以阳离子两性和阴离子形式，，dc分子在 pH <3.3时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 электростатические взаимодействия и существовать в виде катионов, цвиттер-ионов и анионов, а молвекуляы катионными (ДЦГ3+) при рН < 3,3. Yog li ntawd, ntau yam haujlwm ntawm DC thiab cov qauv cuam tshuam ntawm qhov chaw ntawm rGO / nZVI composite 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 muaj nyob ua zwitterion (DCH20) ntawm 3.3 < pH < 7.7 thiab anion (DCH- lossis DC2-) ntawm pH 7.7.Nrog rau kev nce pH ntawm 3 mus rau 7, lub peev xwm adsorption thiab kev ua haujlwm ntawm DC tshem tawm tau nce ntxiv los ntawm 11.2 mg / g (56%) mus rau 17 mg / g (85%) (Daim Duab 6C). Txawm li cas los xij, thaum pH nce mus rau 9 thiab 11, lub peev xwm adsorption thiab kev ua haujlwm tshem tawm tau txo qis me ntsis, los ntawm 10.6 mg / g (53%) mus rau 6 mg / g (30%), raws li. Nrog rau kev nce pH ntawm 3 mus rau 7, DCs feem ntau muaj nyob rau hauv daim ntawv ntawm zwitterions, uas ua rau lawv yuav luag tsis nyiam lossis rov qab nrog rGO / nZVI composites, feem ntau los ntawm kev sib cuam tshuam electrostatic. Raws li pH nce siab dua 8.2, qhov chaw ntawm adsorbent tau them tsis zoo, yog li lub peev xwm adsorption txo qis thiab txo qis vim yog electrostatic repulsion ntawm qhov tsis zoo doxycycline thiab qhov chaw ntawm adsorbent. Qhov sib txawv no qhia tau hais tias DC adsorption ntawm rGO/nZVI composites yog nyob ntawm pH heev, thiab cov txiaj ntsig kuj qhia tau tias rGO/nZVI composites yog qhov tsim nyog ua adsorbents nyob rau hauv cov xwm txheej acidic thiab nruab nrab.
Qhov cuam tshuam ntawm qhov kub thiab txias rau kev nqus ntawm cov kua dej ntawm DC tau ua tiav ntawm (25–55 ° C). Daim duab 7A qhia txog qhov cuam tshuam ntawm qhov kub thiab txias nce rau kev tshem tawm cov tshuaj tua kab mob DC ntawm rGO / nZVI, nws yog qhov tseeb tias lub peev xwm tshem tawm thiab lub peev xwm nqus tau nce ntxiv los ntawm 83.44% thiab 13.9 mg / g mus rau 47% thiab 7.83 mg / g., feem. Qhov kev txo qis tseem ceeb no yuav yog vim muaj kev nce ntxiv ntawm lub zog thermal ntawm DC ions, uas ua rau desorption47.
Cov Nyhuv ntawm Kub rau Kev Tshem Tawm Zoo thiab Lub Peev Xwm Adsorption ntawm CD rau rGO/nZVI Composites (A) [Co = 50 mg L–1, pH = 7, Koob Tshuaj = 0.05 g], Koob Tshuaj Adsorbent rau Kev Tshem Tawm Zoo thiab Kev Tshem Tawm Zoo ntawm CD Cov Nyhuv ntawm Kev Ntsuas Pib rau lub peev xwm adsorption thiab kev ua haujlwm ntawm DC tshem tawm rau 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, koob tshuaj = 0.05 g].
Qhov cuam tshuam ntawm kev nce qhov koob tshuaj ntawm cov khoom sib xyaw ua ke rGO/nZVI los ntawm 0.01 g mus rau 0.07 g ntawm kev tshem tawm zoo thiab lub peev xwm adsorption tau qhia hauv daim duab 7B. Kev nce qhov koob tshuaj ntawm cov adsorbent ua rau muaj kev txo qis hauv lub peev xwm adsorption los ntawm 33.43 mg / g mus rau 6.74 mg / g. Txawm li cas los xij, nrog rau kev nce hauv qhov koob tshuaj adsorbent los ntawm 0.01 g mus rau 0.07 g, qhov kev tshem tawm zoo nce ntxiv los ntawm 66.8% mus rau 96%, uas, raws li, tej zaum yuav cuam tshuam nrog kev nce ntxiv ntawm cov chaw ua haujlwm ntawm qhov chaw nanocomposite.
Kev kawm txog qhov cuam tshuam ntawm qhov pib concentration rau lub peev xwm adsorption thiab kev tshem tawm zoo [25–100 mg L-1, 25°C, pH 7, koob tshuaj 0.05 g] tau kawm. Thaum qhov pib concentration nce ntxiv los ntawm 25 mg L-1 mus rau 100 mg L-1, feem pua ​​​​​​ntawm kev tshem tawm ntawm rGO/nZVI composite txo qis los ntawm 94.6% mus rau 65% (Daim duab 7C), tej zaum vim tsis muaj cov chaw nquag xav tau. . Adsorbs cov concentration loj ntawm DC49. Ntawm qhov tod tes, thaum qhov pib concentration nce ntxiv, lub peev xwm adsorption kuj nce ntxiv los ntawm 9.4 mg/g mus rau 30 mg/g kom txog thaum sib npaug (Daim duab 7D). Qhov kev tsis sib haum xeeb no yog vim muaj kev nce ntxiv ntawm lub zog tsav tsheb nrog qhov pib DC concentration ntau dua li DC ion mass transfer resistance kom ncav cuag qhov chaw 50 ntawm rGO/nZVI composite.
Lub sijhawm sib cuag thiab kev tshawb fawb kinetic lub hom phiaj yog kom nkag siab txog lub sijhawm sib npaug ntawm kev nqus. Ua ntej, qhov ntau ntawm DC adsorbed thaum thawj 40 feeb ntawm lub sijhawm sib cuag yog kwv yees li ib nrab ntawm tag nrho cov nyiaj adsorbed thoob plaws lub sijhawm (100 feeb). Thaum cov DC molecules hauv cov tshuaj sib tsoo ua rau lawv tsiv mus rau qhov chaw ntawm rGO / nZVI composite ua rau muaj kev nqus tseem ceeb. Tom qab 40 feeb, DC adsorption nce maj mam thiab qeeb qeeb kom txog thaum sib npaug tau mus txog tom qab 60 feeb (Daim duab 7D). Txij li thaum muaj qhov tsim nyog tau adsorbed hauv thawj 40 feeb, yuav muaj tsawg dua kev sib tsoo nrog DC molecules thiab tsawg dua qhov chaw nquag yuav muaj rau cov molecules tsis-adsorbed. Yog li ntawd, tus nqi adsorption tuaj yeem txo qis 51.
Yuav kom nkag siab zoo dua txog kev nqus kinetics, cov kab kos ntawm pseudo thawj qhov kev txiav txim (Daim duab 8A), pseudo thib ob qhov kev txiav txim (Daim duab 8B), thiab Elovich (Daim duab 8C) kinetic qauv tau siv. Los ntawm cov kev ntsuas tau los ntawm kev tshawb fawb kinetic (Rooj S1), nws pom tseeb tias tus qauv pseudosecond yog tus qauv zoo tshaj plaws rau kev piav qhia txog kev nqus kinetics, qhov twg tus nqi R2 tau teeb tsa siab dua li lwm ob tus qauv. Kuj tseem muaj qhov zoo sib xws ntawm cov peev xwm nqus tau xam (qe, cal). Qhov kev txiav txim pseudo-thib ob thiab cov nqi sim (qe, exp.) yog cov pov thawj ntxiv tias qhov kev txiav txim pseudo-thib ob yog tus qauv zoo dua li lwm cov qauv. Raws li tau pom hauv Rooj 1, cov nqi ntawm α (tus nqi nqus thawj zaug) thiab β (desorption tas li) lees paub tias tus nqi nqus siab dua tus nqi nqus, qhia tias DC feem ntau adsorb zoo rau ntawm rGO / nZVI52 composite. .
Cov phiaj xwm kinetic adsorption linear ntawm pseudo-second order (A), pseudo-first order (B) thiab Elovich (C) [Co = 25–100 mg l–1, pH = 7, T = 25 °C, dose = 0.05 g].
Cov kev tshawb fawb ntawm adsorption isotherms pab txiav txim siab qhov muaj peev xwm adsorption ntawm adsorbent (RGO / nRVI composite) ntawm ntau yam adsorbate concentration (DC) thiab qhov kub ntawm lub cev. Qhov muaj peev xwm adsorption siab tshaj plaws tau suav los ntawm kev siv Langmuir isotherm, uas qhia tau tias qhov adsorption yog homogeneous thiab suav nrog kev tsim ntawm adsorbate monolayer ntawm qhov chaw ntawm adsorbent yam tsis muaj kev sib cuam tshuam ntawm lawv53. Ob qho qauv isotherm siv dav dav yog cov qauv Freundlich thiab Temkin. Txawm hais tias tus qauv Freundlich tsis siv los xam qhov muaj peev xwm adsorption, nws pab kom nkag siab txog cov txheej txheem adsorption heterogeneous thiab tias qhov chaw seem ntawm adsorbent muaj zog sib txawv, thaum tus qauv Temkin pab kom nkag siab txog cov khoom siv lub cev thiab tshuaj ntawm adsorption54.
Cov Duab 9A-C qhia cov kab kos ntawm Langmuir, Freindlich, thiab Temkin qauv, raws li. Cov nqi R2 xam los ntawm Freundlich (Daim Duab 9A) thiab Langmuir (Daim Duab 9B) kab kos thiab nthuav tawm hauv Rooj 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). Lub peev xwm adsorption siab tshaj plaws (qmax), xam siv Langmuir isotherm qauv, yog 31.61 mg g-1. Tsis tas li ntawd, tus nqi xam ntawm qhov tsis muaj qhov sib cais (RL) yog ntawm 0 thiab 1 (0.097), qhia txog cov txheej txheem adsorption zoo. Txwv tsis pub, qhov Freundlich tas li xam (n = 2.756) qhia txog kev nyiam rau cov txheej txheem nqus no. Raws li tus qauv linear ntawm Temkin isotherm (Daim Duab 9C), qhov adsorption ntawm DC ntawm rGO/nZVI composite yog ib qho txheej txheem adsorption lub cev, txij li b yog ˂ 82 kJ mol-1 (0.408)55. Txawm hais tias qhov adsorption lub cev feem ntau yog mediated los ntawm cov zog van der Waals tsis muaj zog, qhov kev adsorption tam sim no ncaj qha ntawm rGO/nZVI composites xav tau lub zog adsorption qis [56, 57].
Freundlich (A), Langmuir (B), thiab Temkin (C) cov kab adsorption isotherms [Co = 25–100 mg L–1, pH = 7, T = 25 °C, koob tshuaj = 0.05 g]. Daim duab ntawm van't Hoff equation rau DC adsorption los ntawm rGO/nZVI composites (D) [Co = 25–100 mg l-1, pH = 7, T = 25–55 °C thiab koob tshuaj = 0.05 g].
Txhawm rau soj ntsuam qhov cuam tshuam ntawm kev hloov pauv kub ntawm cov tshuaj tiv thaiv rau DC tshem tawm ntawm rGO / nZVI composites, cov txheej txheem thermodynamic xws li kev hloov pauv entropy (ΔS), kev hloov pauv enthalpy (ΔH), thiab kev hloov pauv zog dawb (ΔG) tau suav los ntawm cov qauv 3 thiab 458.
qhov twg \({K}_{e}\)=\(\frac{{C}_{Ae}}{{C}_{e}}\) - thermodynamic equilibrium tas li, Ce thiab CAe - rGO hauv cov kua, feem /nZVI DC concentrations ntawm qhov sib npaug ntawm qhov chaw. R thiab RT yog cov roj tas li thiab qhov kub ntawm adsorption, feem. Plotting ln Ke tawm tsam 1/T muab ib txoj kab ncaj (Daim duab 9D) uas ∆S thiab ∆H tuaj yeem txiav txim siab.
Tus nqi ΔH tsis zoo qhia tias cov txheej txheem yog exothermic. Ntawm qhov tod tes, tus nqi ΔH yog nyob rau hauv cov txheej txheem adsorption lub cev. Cov nqi ΔG tsis zoo hauv Rooj 3 qhia tias adsorption yog ua tau thiab spontaneous. Cov nqi tsis zoo ntawm ΔS qhia txog kev txiav txim siab siab ntawm cov molecules adsorbent ntawm cov kua interface (Rooj 3).
Rooj 4 piv rau cov rGO/nZVI composite nrog lwm cov adsorbents uas tau tshaj tawm hauv kev tshawb fawb yav dhau los. Nws yog qhov tseeb tias cov VGO/nCVI composite muaj peev xwm adsorption siab thiab tej zaum yuav yog cov khoom siv cog lus rau kev tshem tawm cov tshuaj tua kab mob DC ntawm dej. Tsis tas li ntawd, qhov adsorption ntawm rGO/nZVI composites yog ib qho txheej txheem ceev nrog lub sijhawm sib npaug ntawm 60 feeb. Cov khoom adsorption zoo heev ntawm cov rGO/nZVI composites tuaj yeem piav qhia los ntawm cov nyhuv synergistic ntawm rGO thiab nZVI.
Cov Duab 10A, B qhia txog lub tswv yim zoo 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 qhov cuam tshuam ntawm pH rau kev ua haujlwm ntawm DC adsorption, nrog rau kev nce hauv pH ntawm 3 txog 7, DC adsorption ntawm rGO/nZVI composite tsis raug tswj los ntawm kev sib cuam tshuam electrostatic, vim nws ua haujlwm ua zwitterion; yog li ntawd, kev hloov pauv hauv tus nqi pH tsis cuam tshuam rau cov txheej txheem adsorption. Tom qab ntawd, lub tshuab adsorption tuaj yeem tswj tau los ntawm kev sib cuam tshuam tsis yog electrostatic xws li hydrogen bonding, hydrophobic effects, thiab π-π stacking sib cuam tshuam ntawm rGO/nZVI composite thiab DC66. Nws paub zoo tias lub tshuab ntawm aromatic adsorbates ntawm cov nplaim ntawm cov txheej graphene tau piav qhia los ntawm π-π stacking sib cuam tshuam ua lub zog tsav tsheb tseem ceeb. Cov khoom sib xyaw yog cov khoom siv txheej zoo ib yam li graphene nrog qhov siab tshaj plaws ntawm 233 nm vim yog qhov hloov pauv π-π *. Raws li qhov muaj plaub lub nplhaib aromatic hauv cov qauv molecular ntawm DC adsorbate, peb tau xav tias muaj ib txoj hauv kev ntawm π-π-stacking kev sib cuam tshuam ntawm aromatic DC (π-electron acceptor) thiab thaj chaw nplua nuj hauv π-electrons rau ntawm RGO nto. /nZVI composites. Tsis tas li ntawd, raws li pom hauv daim duab 10B, FTIR kev tshawb fawb tau ua los kawm txog kev sib cuam tshuam molecular ntawm rGO/nZVI composites nrog DC, thiab FTIR spectra ntawm rGO/nZVI composites tom qab DC adsorption tau pom hauv Daim Duab 10B. 10b. Ib lub ncov tshiab tau pom ntawm 2111 cm-1, uas sib raug rau lub cev vibration ntawm C = C daim ntawv cog lus, uas qhia txog qhov muaj cov pab pawg ua haujlwm organic sib xws ntawm qhov chaw ntawm 67 rGO/nZVI. Lwm cov ncov hloov ntawm 1561 mus rau 1548 cm-1 thiab ntawm 1399 mus rau 1360 cm-1, uas kuj lees paub tias π-π kev sib cuam tshuam ua lub luag haujlwm tseem ceeb hauv kev nqus ntawm graphene thiab cov pa phem organic 68,69. Tom qab DC adsorption, qhov muaj zog ntawm qee pawg uas muaj oxygen, xws li OH, txo qis 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 composite tshwm sim feem ntau vim yog π-π stacking kev sib cuam tshuam thiab H-bonds.
Lub tswv yim tsim nyog ntawm kev nqus cov tshuaj tua kab mob DC los ntawm rGO / nZVI thiab nZVI complexes (A). FTIR adsorption spectra ntawm DC ntawm rGO / nZVI thiab nZVI (B).
Qhov muaj zog ntawm cov kab nqus ntawm nZVI ntawm 3244, 1615, 1546, thiab 1011 cm-1 nce tom qab DC adsorption ntawm nZVI (Daim Duab 10B) piv rau nZVI, uas yuav tsum muaj feem cuam tshuam nrog kev sib cuam tshuam nrog cov pab pawg ua haujlwm ntawm cov carboxylic acid O pawg hauv DC. Txawm li cas los xij, qhov feem pua ​​qis dua ntawm kev sib kis hauv txhua qhov kab uas tau pom qhia tias tsis muaj kev hloov pauv tseem ceeb hauv kev ua haujlwm adsorption ntawm phytosynthetic adsorbent (nZVI) piv rau nZVI ua ntej cov txheej txheem adsorption. Raws li qee qhov kev tshawb fawb tshem tawm DC nrog nZVI71, thaum nZVI tshuaj tiv thaiv nrog H2O, cov electrons raug tso tawm thiab tom qab ntawd H + siv los tsim cov hydrogen nquag uas txo qis heev. Thaum kawg, qee cov tshuaj cationic txais cov electrons los ntawm cov hydrogen nquag, ua rau -C = N thiab -C = C-, uas yog vim qhov kev sib cais ntawm lub nplhaib benzene.