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1.
Metal ferrites nanocrystallites, MFe2O4 (M = Mn, Co, Ni, Zn) were prepared by coprecipitation method and characterized by a combination of physico‐chemical and spectroscopic techniques. MFe2O4 nanoparticles having particle size in the range 10–35 nm were tested as catalysts in the oxidation of o‐phenylenediamine (OPD) to 2,3–diaminophenazine (DAP) using hydrogen peroxide as oxidant at room temperature. Kinetic data was collected for the catalytic oxidation of OPD to DAP by monitoring the UV–vis absorbance at 415 nm and fit well to the Michaelis–Menten model yielding kinetic parameters Km (Michaelis–Menten constant) and Vmax (maximum rate of reaction). MnFe2O4 nanoparticles provide the highest catalytic activity in the oxidation of OPD to DAP at room temperature. A colorimetric method was developed based on the MnFe2O4/OPD system for the detection of H2O2 in reaction solution. The method has a detection limit of 30 μM for H2O2 and wide linear range.  相似文献   

2.
An efficient colorimetric and fluorescent chemodosimeter for Fe3+ ions has been developed. The visual and fluorescent behaviors of the receptor toward various metal ions were investigated. The receptor shows exclusive response toward Fe3+ ions and also distinguishes Fe3+ from other cations by color change and unusual fluorescence enhancement in aqueous solution (DMSO/H2O = 4/1, v/v). Thus, the receptor can be used as a colorimetric and fluorescent sensor for the determination of Fe3+ ion. The visual color detection limit and the fluorescence detection limit of the receptor towards Fe3+ are (1.42 ± 0.01) × 10‐6 M and (7.57 ± 0.04) × 10‐8 M, respectively. The fluorescence microscopy experiments showed that the receptor is efficient for detection of Fe3+ in vitro, developing a good image of the biological organelles. The sensing mechanism is proven to be a hydrolysis process  相似文献   

3.
Hou  Chen  Fu  Linhui  Wang  Yang  Chen  Wenqiang  Chen  Fang  Zhang  Sufeng  Wang  Jianzhi 《Cellulose (London, England)》2021,28(14):9253-9268

Rapid and accurate detection of phenolic wastewater from industries has created global concern. Herein, core–shell magnetic cellulose nanocrystal supported MOF (Fe3O4/CNC@ZIF-8) with robust peroxidase-like activity was synthesized with tannic acid as modifier and bridge. The peroxidase-mimic catalytic activity of as-prepared Fe3O4/CNC@ZIF-8 was further investigated using o-phenylenediamine (OPD) as peroxidase substrates in the presence of H2O2. Moreover, the experimental conditions were optimized and the kinetic analysis results showed that Fe3O4/CNC@ZIF-8 had higher affinity towards both the substrate OPD and H2O2 than horseradish peroxidase (HRP). Finally, a phenol colorimetric assay with a linear range of 2–200 µM and a detection limit of 0.316 µM was constructed. The catalytic mechanism of Fe3O4/CNC@ZIF-8 with phenol was further investigated by fluorescence test and the generated ·OH was proved to act a crucial role to produce quinoid radicals. Additionally, the synthesized magnetic material had excellent stability and recyclability and ease to separation. These results suggest that the Fe3O4/CNC@ZIF-8 may be one of the promising candidates as peroxidase mimic for colorimetric detection of phenol.

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4.
Degradation of methyl tert-butyl ether (MTBE) with Fe2+/H2O2 was studied by purge-and-trap gas chromatography-mass spectrometry. MTBE was degraded 99% within 120 min under optimum conditions. MTBE was firstly degraded rapidly based on a Fe2+/H2O2 reaction and then relatively slower based on a Fe3+/H2O2 reaction. The dissolved oxygen decreased rapidly in the Fe2+/H2O2 reaction stage, but showed a slow increase in the Fe3+/H2O2 reaction stage. tert-Butyl formate, tert-butyl alcohol, methyl acetate and acetone were identified as primary degradation products by mass spectrometry. A preliminary reaction mechanism involving two different pathways for the degradation of MTBE with Fe2+/H2O2 was proposed. This study suggests that degradation of MTBE can be achieved using the Fe2+/H2O2 process.  相似文献   

5.
New nanocomposites, Fe3O4@Au–FITC, were prepared and explored to develop a fluorescent detection of Pb2+. The Fe3O4@AuNPs–FITC nanocomposites could be etched by Pb2+ in the presence of Na2S2O3, leading to fluorescence recovery of FITC quenched by Fe3O4@Au nanocomposites. With the increase of Pb2+ concentration, the fluorescence recovery of Fe3O4@AuNPs–FITC increased gradually. Under optimized conditions, a detection limit of 5.2 nmol/L of Pb2+ with a linear range of 0.02–2.0 µmol/L were obtained. The assay demonstrated negligible response to common metal ions. Recoveries of 98.2–106.4% were obtained when this fluorescent method was applied in detecting Pb2+ spiked in a lake-water sample. The above results demonstrated the high potential of ion-induced nanomaterial etching in developing robust fluorescent assays.  相似文献   

6.
Here, we report an ultra-sensitive and colorimetric sensor for the detection of Fe3+ or Cu2+ successively using glutathione-functionalized Au nanoclusters (GSH-AuNCs). For GSH-AuNCs can catalytically oxidize peroxidase substrates, such as 3, 3′, 5, 5′-tetramethylbenzidine (TMB), colored products are formed in the presence of H2O2. While upon the addition of Fe3+ or Cu2+ into the GSH-AuNCs-TMB-H2O2 system, diverse color and absorbance of the system was obtained due to the self oxidation of Fe3+ and the inhibition of peroxidase-like activity of GSH-AuNCs. With the introduction of ethylene diamine tetraacetic acid (EDTA) or ammonium fluoride (NH4F) to GSH-AuNCs-TMB-H2O2+Cu2+ system or GSH-AuNCs-TMB-H2O2+Fe3+ system respectively, a restoration of color and absorbance of system was realized. On the basis of above phenomenon, a colorimetric and quantitative approach for detecting Fe3+ and Cu2+ was developed with detection limit of 1.25 × 10−9 M and 1.25 × 10−10 M respectively. Moreover, the concentration of Fe3+ and Cu2+ in human serums was also accurate quantified by this method. So this design strategy realized the simple and simultaneous detection of Fe3+ and Cu2+, suggesting significant potential in clinical diagnosis.  相似文献   

7.
A colorimetric method is described for the determination of ferrous ion (Fe2+) with high sensitivity and selectivity. The method is based on catalytic etching of gold nanorod (NR). In an acid condition, Fe2+ reacts with H2O2 to produce superoxide radical (O2 ??) that etches gold NRs from the low energy surface along the longitudinal direction preferentially. As a result, the changes in the absorption spectrum and color of gold NR can be measured and also can be detected visually. Under the optimal conditions, the assay has very low detection limit (13.5 nM) and a linear response in a concentration range of 75 to 1 μM. The method was applied to the determination of Fe2+ in spiked samples of fetal bovine serum and also transferred to a kind of test stripe for use in fast practical applications. A unique colorimetric sensing method is demonstrated for the colorimetric detection of Fe2+, again based on the oxidation of gold nanorods which leads to the blue-shift of the absorption.
Graphical abstract A unique colorimetric sensing method was shown for the colorimetric detection of Fe2+. Fe2+reacts with H2O2 to generate superoxide radical that oxidize gold nanorods. This leads to a color change from blue-green to pink.
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8.
A type of fluorescent–magnetic dual‐function nanocomposite, Fe3O4@SiO2@P‐2, was successfully obtained by Cu+‐catalyzed click reaction between acetylene (C?C? H)‐substituted carbazole‐based conjugated polymer ( P‐2) and azide‐terminated silica‐coated magnetic iron oxide nanoparticles (Fe3O4@SiO2–N3). Optical and magnetization analyses indicate that Fe3O4@SiO2@P‐2 exhibits stable fluorescence and rapid magnetic response. The fluorescence of Fe3O4@SiO2@P‐2 was quenched significantly in the presence of I? and gave a detection limit (DL) of ~8.85 × 10?7 M. Given the high binding constant and matching ratio between Hg2+ and I?, the fluorescence of Fe3O4@SiO2@P‐2/I? complex recovered efficiently with the addition of Hg2+. A DL of ~4.17 × 10?7 M was obtained by this probing system. Recycling of Fe3O4@SiO2@P‐2 probe was readily achieved by simple magnetic separation. Results indicate that Fe3O4@SiO2@P‐2 can be used as an “on–off–on” fluorescent switchable and recyclable Hg2+ probe. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3636–3645  相似文献   

9.
Experimental data on the equilibria Fe2+/Fe3+ and SO3 2−/SO4 2− in the system Fe(OH)3(H2SO4)-Na2SO3-H2O are presented. The quantitative relations between the reduction of Fe(III) and the precipitation of FeSO3·2.5H2O as a Fe2O3 precursor have considered graphically.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 1, 2005, pp. 41–44.Original Russian Text Copyright © 2005 by Vasekha, Motov.  相似文献   

10.
General kinetic relations were established for the first step of oxidation of Acid Blue 80 in weakly acidic, neutral and basic media in the following systems: Fe2+-H2O2, Mn2+-HCO3 --H2O2, and Cu2+-phenanthroline-H2O2. The rate constant for the reaction of hydroxyl radical with the dye and the dependence of the degree of bleaching upon oxidant and catalyst concentrations were determined.  相似文献   

11.
The present study reports simultaneous mineralisation and biodetoxification of Ponceau S (3-hydroxy-4-(2-sulfo-4-[4-sulfophenylazo]phenylazo)-2,7-naphthalenedisulfonic acid sodium salt), an azo dye, by UV light assisted oxidation with hydroxyl and sulfate radicals. Metal ion catalysts used in the work were: Fe2+ and Ag+, and the oxidants used were: hydrogen peroxide and S2O82?. Strategies adopted to make the processes environmentally benign and economically viable by achieving maximum mineralisation in the shortest possible time are described. Mineralisation efficiency (Em) of various systems was found to follow the order: Em(Fe2+/H2O2/UV) > Em(Fe2+/S2O82?/UV) > Em(Ag+/H2O2/UV) ≈ Em(Ag+/S2O82?/UV). Thus, Fe2+ and HP are the most suitable metal ion catalyst and oxidant respectively, showing higher efficiency at pH 3 followed by that at pH 6.6. It is possible to enhance the Fe2+/H2O2/UV process electrical energy efficiency by maintaining the concentration of Fe at either 0.05 mM or 0.03 mM and that of the oxidant at 2.5 mM. The bioassay study revealed that the Fe2+/S2O82?/UV process biodetoxification efficiency is higher at pH 3 (93.7 %) followed by that at pH 6.6 (80.1 %) at the concentration of Fe 2+ and S2O82? of 0.03 mM and 2.5 mM, respectively. Thus, not only the concentration of Fe2+, but also the nature of the oxidant and pH play an important role in the biodetoxification process and S2O82? possesses higher biodetoxification efficiency than H2O2.  相似文献   

12.
A small organic molecule P was synthesized and characterized as a fluorometric and colorimetric dual-modal probe for Hg2+. The sensing characteristics of the proposed probe for Hg2+ were studied in detail. A fluorescent enhancing property at 583 nm (>30 fold) accompanied with a visible colorimetric change, from colorless to pink, was observed with the addition of Hg2+ to P in an ethanol-water solution (8:2, v/v, 20 mM HEPES, pH 7.0), which would be helpful to fabricate Hg2+-selective probes with “naked-eye” and fluorescent detection. Meanwhile, cellular experimental results demonstrated its low cytotoxicity and good biocompatibility, and the application of P for imaging of Hg2+ in living cells was satisfactory.  相似文献   

13.
In this work, green fluorescent carbon dots with a high relative quantum yield of 74.13% were synthesized by using one-pot hydrothermal hydrolysis of m-phenylenediamine (mPD) and PEG 1500 in H2SO4 solution at 180 °C for 10 h (mPD-CDs). In the presence of mPD-CDs, Fe2+ can form a complex with 1,10-phenanthroline (Fe(II) – phenanthroline) without interference from mPD-CDs, which has an absorption peak centered at 512 nm and its absorbance is sensitive to the concentration of Fe(II) – phenanthroline. Accordingly, a colorimetric method for the detection of Fe2+ was constructed with a limit of detection (LOD) of 2.98 μM. Moreover, the absorption spectrum of the Fe (II)-phenanthroline complex is overlapping with the excitation and emission spectra of mPD-CDs located at 440 and 516 nm, respectively, resulting in an inner filter effect (IFE) which is sensitive to the concentration of Fe(II) – phenanthroline. Correspondingly, a fluorimetric method for the detection of Fe2+ based on the mPD-CDs/phenanthroline system was built with a LOD as low as 0.59 μM. Therefore, colorimetric and fluorimetric dual mode detection of Fe2+ in aqueous solution can be achieved by a carbon dots/phenanthroline system.  相似文献   

14.
X-Ray and uv photoelectron spectra of FeO, Fe2O3, and Fe3O4 have been studied along with those of a few model compounds. It has been possible to assign distinct bands due to Fe2+ and Fe3+ in the 3d, 3p, 3s, and 2p bands of Fe3O4. The spectra of Fe3O4 do not show major changes through the Verwey transition.  相似文献   

15.
TG experiments on the hydrogen reduction of α-Fe2O3 were carried out to elucidate the influence of the preparation history of the oxide on its reactivity. α-Fe2O3 samples were prepared by the thermal decomposition of seven iron salts in a stream of oxygen, air or nitrogen at temperatures of 500–1200°C for 1 h. Thirteen metal ions such as Cu2+, Ni2+, etc. were used as doping agents. The reactivity of the oxide was indicated by the initial reduction temperature (Ti. α-Fe2O3 prepared at lower temperatures showed lower Ti values and the reduction proceeded stepwise (Fe2O3 → Fe3O4 → Fe). Ti values increased with the rise in the preparation temperature of the oxide. The oxides prepared at higher temperatures showed that two reduction steps (Fe2O3 → Fe3O4 → Fe) proceed simultaneously. the preparation in oxygen gave higher Ti than that in air or nitrogen. The doping by metal ions, except Ti4+, lowered the Ti of α-Fe2O3. The Cu2+ ion showed the lowest Ti, while Ti4+ showed the highest Ti and the inhibition effect.The reduction process was expressed by two equations; Avrami—Erofeev's equation for α-Fe2O3 → Fe3O4 and Mampel's equation for Fe3O4 → Fe.  相似文献   

16.
A cyclometalated ruthenium (II) complex 1 [(Ru (Phen)2(Pbznh)]+ PF6 (Phen = 1,10-phenanthroline and Pbznh = N-(4-(pyridine-2-yl)benzylidene) nicotinohydrazide) with nicotinohydrazide as a functional group was synthesized and characterized. Changes of its absorption spectra and color induced by Cu2+ and Fe3+ were systematic investigated. The results demonstrated that complex 1 could be served as a colorimetric probe to fast, selective and sensitive detection of Cu2+ and Fe3+ both in acetonitrile and filter paper based strips. Upon addition of Cu2+ and Fe3+ to solution of probe 1 , solution color changed from pink to colorless and light yellow respectively, and their corresponding detection limit were calculated to be 3.26 × 10−8 M and 3.12 × 10−7 M. Moreover, color of test papers with 1 changed from pink to colorless/yellow when Cu2+/Fe3+ were dropwise added. Therefore, it can be used as a desirable ‘naked-eye’ indicator candidate for Cu2+ and Fe3+.  相似文献   

17.
The thermodynamic properties of the Fe3O4ZnFe2O4 spinel solid solution were determined at 900°C by the use of the solid electrolyte galvanic cell Fe2O3 + Fe3O4|O2?|Fe2O3 + ZnxFe3?xO4The activity values obtained exhibit slight negative deviation from the ideal solution model. An analysis of the free energy of mixing of the spinel solid solution provided information on the distribution of cations between the tetrahedral and octahedral sites of the spinel lattice. This is the basis for the estimation of the free energy of formation of pure zinc ferrite from oxides. ΔG0ZnFe2O4 = ?2740 ? 1.6 T cal mole?1  相似文献   

18.
A commercially-available sulfonphthalein derivative was demonstrated to be a chemodosimeter for Fe2+ and its sensing behavior was further investigated by UV-vis spectroscopy in aqueous media under the optimum conditions. In the presence of chlorophenol red (CPR) and H2O2, the absorption maximum at 435 nm decreased upon addition of Fe2+, resulting in a significant color change of the CPR solution from yellow to colorless. The chemosensor system did not show significant responses to a series of other metal ions including Al3+, Zn2+, Cd2+, Hg2+, Mn2+, Co2+, Fe3+, Ni2+, Cu2+, La3+, Ce4+, Th4+, Pd2+, Pb2+, Sb3+, Cr3+, Au3+, Ag+, Nd3+, Sm3+, alkali and alkaline earth metal cations, allowing for highly selective naked-eye detection of Fe2+. Quantitative analysis was carried out kinetically for practicable the Fe2+ assay when either fixed time method or the initial rate method was applied. When the detecting time was set, the decrease of absorbance signal was linear with Fe2+ concentration in the range of 0 to 7.50 × 10?5 mol L?1 and the regression equation was ΔA = 0.00759 + 0.00593C Fe with a correlation coefficient r = 0.9953. The chemodosimetric system has employed an irreversible Fenton reagent-promoted oxidation of the CPR free chromophore and the hydroxyl radicals were generated in the presence of both Fe2+ and hydrogen peroxide. The mechanistic interpretation of the signaling process was partially confirmed by the radical scavenging experiment and the FT-IR analysis of the intermediates formed at different reaction periods.  相似文献   

19.
A hydrophobic organic monomer GRBE with a polymerizable methacrylester moiety had been synthesized by reaction of rhodamine B‐ethanediamine with glycidyl methacrylate. A water‐soluble polymeric chemosensor poly(VP‐GRBE) had been prepared via copolymerization with a hydrophilic comonomer (vinylpyrrolidone) and GRBE, which was able to sense environmentally poisonous cations in completely aqueous media. The chemosensor was a derivative of rhodamine B, which behaved as a fluorescent and chromogenic sensor toward various heavy cations, particularly Cr3+, Fe3+, and Hg2+. Titration curves of Cr3+, Fe3+, and Hg2+ were constructed using rapid, cheap, and widely available technique of fluorescence spectroscopies. The detection limits for Cr3+, Fe3+, or Hg2+ ions were found to be 2.20 × 10?12, 2.39 × 10?12, and 1.11 × 10?12 mol/l in the same medium, respectively. Moreover, a colorimetric response from the polymeric chemosensor permitted the detection of Cr3+, Hg2+, or Fe3+ by “naked eye” because of the development of a pink or brown yellow color when Cr3+, Hg2+, or Fe3+ cations interacted with the copolymer in aqueous media. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

20.
A fluorescent “turn‐on” probe for Fe3+ was investigated in an aqueous system based on a boron 2‐(2′‐pyridyl) imidazole complex (BOPIM‐dma). BOPIM‐dma shows weak or no fluorescence in polar solvents due to twisted intramolecular charge transfer, but the addition of Fe3+ to BOPIM‐dma leads to fluorescence switch‐on responses. The binding is highly selective to Fe3+ over other metal ions, indicating that BOPIM‐dma is a chemodosimeter for Fe3+. Furthermore, the existence of S2O32− could much enhance and stabilize the emission significantly, indicating that the BOPIM‐dma/Fe3+/S2O32− complexes are a strong fluorescence system, and can be used as a sensitive detector for Fe3+, with the limit of detection of 6.0 × 10−7 mol L−1.  相似文献   

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