Trace Amounts Of Fe3 Research Articles

Quaternary Ammonium-Mediated Delamination of Europium-Based Metal-Organic Framework into Ultrathin Nanosheets for the Selective Photoelectrochemical Sensing of Fe3.

Structural delamination of bulk layered metal-organic frameworks (MOFs) remains a great challenge, largely owing to a lack of general synthetic strategies. Here, we reported a simple solvent-free intercalation strategy for the delamination of rare-earth-based MOF (RE-MOF) with a topology structure of MIL-78 by tuning the chain length of quaternary ammonium salts. Four types of quaternary ammonium salts, involving tetraethylammonium bromide (TEAB), tetrapropylammonium bromide (TPAB), tetrabutylammonium bromide (TBAB), and hexadecyl trimethyl ammonium bromide (CTAB) were introduced to investigate their intercalation capabilities. It is evident in our case that the interruption/intercalation behavior of quaternary ammonium salts differs with their steric structures, and the chain-like CTAB can induce obvious delamination of MIL-78 crystals. Particularly, the CTAB-intercalated ultrathin Eu-based MIL-78 nanosheets exhibited unique selective photoelectrochemical sensing property toward trace amounts of Fe3+ ions in aqueous solution with a detection limit of 0.0899 μM at a signal-to-noise ratio of 3. These results demonstrated a green bottom-up strategy to obtain high-quality RE-MOF nanosheets for potential photocurrent response applications.

Novel low-temperature H2S removal technology by developing yellow phosphorus and phosphate rock slurry as absorbent

Recycling hazardous gas of H2S is one of the most important strategies to promote sustainable development. Herein, a novel method regarding purifying H2S is proposed by using yellow phosphorus and phosphate rock slurry as absorbent. The H2SO4, formed in situ by H2S conversion, can be devoted to decompose phosphate rock, and the spent absorption slurry was applied as raw material for the production of phosphorus chemical products. According to the characterization analysis, it was found that H2S was first oxidized to SO2 via O2 as well as O3 induced by P4. Subsequently, the generated SO2 dissolved rapidly in water to form H2SO4, and then reacted with the main component of phosphate rock, CaMg(CO3)2. Most notably, the active substances, such as, O3, SO4•- and OH•, produced in the reaction process, can oxidize H2S and HS- to these sulfur products. In addition, trace amounts of Fe3+ and Mn2+ that were dissolved from phosphate rock displayed a promotional effect on the formation of active substances. Consequently, as high as 85% of H2S removal efficiency can be obtained even under acidic condition and low temperature. The proposed H2S purification method offers a promising option for sulfur recovery and H2S pollution control.

Maillard Reaction Intermediates and Related Phytochemicals in Black Garlic Determined by EPR and HPLC Analyses.

The Maillard reaction intermediates and related phytochemicals in garlic (Allium sativum L.), which was heated for various lengths of time, using X-band (9 GHz) electron paramagnetic resonance (EPR) and high performance liquid chromatography (HPLC) were investigated. Non-spin-trap and non-destructive EPR detected the total reaction intermediates (radicals). The g-value of the signal was 2.004. The signal with a peak-to-peak linewidth (ΔHpp) was approximately 0.67 milli Tesla (mT). The values of the intermediates are suggestive of organic compounds. The garlic darkened in color with the increasing number of heating days. Melanoidin, responsible for darkening of the garlic, was detected at an absorbance of 400 nm. Analysis of the correlation between the EPR intensity and melanoidin absorbance showed a good correlation coefficient (0.98). In addition, 5-hydroxymethyl furfural (5-HMF) and total phenolic compounds increased with the increasing number of heating days. Moreover, trace amount of Fe3+ was observed in the black garlic by EPR. Non-destructive EPR is a useful method for evaluating not only Maillard reaction intermediates, but also the pigment associated with the reaction processes.

Ordered mesoporous silica encapsulated carbon quantum dots and its application in Fe3+ detection

The nanocomposites prepared by the combination of SiO2 and carbon quantum dots (CQDs) have the advantages of low toxicity, high fluorescence intensity, high biocompatibility and good water solubility, which greatly broaden its application range. Nevertheless, if only SiO2 and CQDs are simply combined without any structural design, the stability of the nanocomposites will be poor, which will affect its practical application value. In this work, we first synthesized ordered mesoporous silica (OMS) rapidly in aqueous solution by a facile method (30 min), and then generated CQDs in situ in the mesoporous channels of OMS by hydrothermal method to obtain CQDs@OMS fluorescent nanocomposites. The chemical structure and morphology of OMS and CQDs@OMS were characterized by FT-IR, XRD, SAXRD and TEM, indicating that CQDs was successfully encapsulated in OMS. The stability test results of CQDs@OMS indicate that CQDs can be stably present in the mesoporous channels of OMS, and the fluorescence intensity of CQDs@OMS nanocomposites is almost independent of ionic strength, pH and storage time. The optical performance results show that the optimal excitation wavelength of CQDs@OMS nanocomposites is about 340 nm, the emission wavelength is about 440 nm. Using CQDs@OMS nanocomposites as fluorescent probes to detect Fe3+, it was found that CQDs@OMS responded very quickly to Fe3+. The fluorescence quenching intensity of CQDs@OMS has a good linear relationship with the concentration of Fe3+ in the range of 25–750 μM. Therefore, the trace amount of Fe3+ in solution can be calculated by measuring the relative magnitude of fluorescence intensity.

Guest-Induced Ultrasensitive Detection of Multiple Toxic Organics and Fe3+ Ions in a Strategically Designed and Regenerative Smart Fluorescent Metal-Organic Framework.

Luminescent metal-organic frameworks (LMOFs) are promising functional materials for sustainable applications, where an analyte-induced multiresponsive system with good recyclability is beneficial for detecting numerous lethal pollutants. We designed and built the dual-functionalized, three-dimensional Zn(II)-framework [Zn3( bpg)1.5( azdc)3]·(DMF)5.9·(H2O)1.05 (CSMCRI-1) using an -OH group-integrated bpg linker and a -N═N- moiety containing H2 azdc ligand, which functions as a unique tetrasensoric fluorescent probe. The activated CSMCRI-1 (1') represents the hitherto unreported pillar-layer framework for extremely selective fluorescence quenching by nitrofurazone antibiotics as well as explosive nitro-aromatic 2,4,6-trinitrophenol, where ultrasensitive detection is achieved for both the electron-lacking analytes. Impressively, 1' represents the first ever MOF for significant fluorescence "turn-on" detection of toxic and electron-rich 4-aminophenol in the concurrent presence of isomeric analogues. Density functional theory calculations highlight the specific importance of pillar functionalization in the "turn-on" or "turn-off" responses of 1' by electronically divergent toxic organics and provide further proof of supramolecular interactions between the framework and analytes. The fluorescence intensity of 1' dramatically quenches by a trace amount of Fe3+ ions over other competing metal ions, alongside visible colorimetric change of the framework in solid and solution phase upon Fe3+ encapsulation. The sensing ability of 1' remains unaltered for multiple cycles toward all lethal pollutants. The sensing mechanism is attributed to both dynamic and static quenching as well as resonance energy transfer, which strongly comply with the predictions of theoretical simulations. Considering the long-term and real-time monitoring, AND as well as OR molecular logic gates are constructed based on the discriminative fluorescence response for each analyte that provides a platform to fabricate smart LMOFs with multimode logic operations.

Responses of Acidithiobacillus thiooxidans A01 to Individual and Joint Nickel (Ni2+) and Ferric (Fe3+)

Acidithiobacillus thiooxidans A01 is widely used in bioleaching processes and commonly thrives in most metal-rich environments. However, interactions between different heavy metals remain obscure. In this study, we elaborated the effect of ferric iron on the growth and gene expression of At. thiooxidans A01 under the stress of nickel. The results showed that 600 mM Ni2+ completely inhibited the growth and sulfur metabolism of At. thiooxidans A01. However, trace amounts of Fe3+ (0.5 mM) facilitated the growth of At. thiooxidans A01 in the presence of 600 mM Ni2+. With the addition of 5 mM Fe3+, the maximum cell density reached 1.84 × 108 cell/mL, and pH value was 0.95. In addition, metal resistance-related and sulfur metabolism genes were significantly up regulated with extra ferric iron. Taking the whole process into account, the promoting effect of Fe3+ addition can be attributed to the following: (1) alleviation of the effects of Ni2+ toxicity and restoring the growth of At. thiooxidans A01, (2) a choice of multiple pathways to export nickel ion and producing precursor of chelators of heavy metals. This can suggest that microorganisms may widely exhibit metabolic activity in iron-rich environments with heavy metals. Our study will facilitate the technique development for the processing of ore bodies with highly challenging ore compositions.

A luminescent metal-organic framework with helical SBUs for highly effective detection of Fe3+ ions

A luminescent 3D metal-organic framework, [CdL(H2O)]·1DMF·1.5H2O (1, L = 1-(4-carboxyphenyl)-5-methyl-2,5-dihydro-1H-pyrazole-3-carboxylic acid, DMF = N,N-dimethylformamide), has been successfully synthesized and structurally characterized. The overall structure of 1 contains hexagonal channels and is constructed by helical SBUs with etb topology. Interestingly, compound 1 exhibits good fluorescence intensity in DMF and can be quenched by trace amounts of Fe3+ ions. The Ksv values of compound 1 towards Fe3+can reach up to 3.5 × 104 which surpass some MOFs materials. More importantly, compound 1 is also a recyclable luminescent sensor which can be potentially applied in detecting Fe3+.

Fluorescent Porous Carbazole-Decorated Copolymer Monodisperse Microspheres: Facile synthesis, Selective and Recyclable Detection of Iron (III) in Aqueous Medium.

We demonstrate an environmentally friendly one-step soap-free emulsion polymerization strategy to develop fluorescent carbazole-based copolymer monodisperse microspheres for highly sensitive and selective detection of Fe3+ . The copolymer microspheres feature a stable spherical morphology with a narrow size distribution through regulating N-vinylcarbazole (NVCz) content (1.25-10.0 wt.%). Notably, the as-made microspheres exhibit a strong luminescence, tunable emission intensity and specific surface areas. Interestingly, the fluorescence of the copolymer microspheres can be selectively quenched by trace amounts of Fe3+ due to the oxidation of carbazole, and the quenching fluorescence can be facilely recovered by reduction with NaBH4 . Its excellent sensing performance is shown in terms of high sensitivity (low limit of detection, 1.3 μm), excellent selectivity, and rapid response rate, due to the porous nature of the copolymer microspheres. These results illustrate the copolymer microspheres obtained by simple preparative procedure without using expensive or toxic raw materials would serve as a high performance sensor for highly selective and recyclable detection of Fe3+ in aqueous medium.

Recovery of Scandium from Leachate of Sulfation-Roasted Bayer Red Mud by Liquid–Liquid Extraction

The leachate obtained from sulfation-roasted Bayer red mud is suitable for extraction of scandium by liquid–liquid solvent extraction because it contains trace amounts of Fe3+ and Si4+. In this study, a completely new metallurgical process for selective recovery of scandium from Bayer red mud was proposed. The extraction performances of Sc3+, Fe3+, Al3+, Si4+, Ca2+, and Na+ from synthetic leachate of sulfation-roasted red mud were first investigated using organophosphorus extractants (di-2-ethylhexyl phosphoric acid P204 and 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester P507) and carboxylic acid extractant (Versatic acid 10). It shows that P204 has an excellent extraction ability and that it can be applied to the scandium recovery. P507 and Versatic acid 10 are much poorer in performance for selective extraction of scandium. In the leachate of sulfation-roasted red mud, approximately 97% scandium can be recovered using a P204/sulfonated kerosene (1% v/v) extraction system under the condition of an organic-to-aqueous phase ratio of 10:1 and with an extraction temperature of 15°C.

Stable Zr(IV)-Based Metal–Organic Frameworks with Predesigned Functionalized Ligands for Highly Selective Detection of Fe(III) Ions in Water

Metal-organic frameworks are a class of attractive materials for fluorescent sensing. Improvement of hydrolytic stability, sensitivity, and selectivity of function is the key to advance application of fluorescent MOFs in aqueous media. In this work, two stable MOFs, [Zr6O4(OH)8(H2O)4(L1)2] (BUT-14) and [Zr6O4(OH)8(H2O)4(L2)2] (BUT-15), were designed and synthesized for the detection of metal ions in water. Two new ligands utilized for construction of the MOFs, namely, 5',5‴-bis(4-carboxyphenyl)-[1,1':3',1″:4″,1‴:3‴,1''''-quinquephenyl]-4,4''''-dicarboxylate (L1) and 4,4',4″,4‴-(4,4'-(1,4-phenylene)bis(pyridine-6,4,2-triyl))tetrabenzoate (L2), are structurally similar with the only difference being that the latter is functionalized by pyridine N atoms. The two MOFs are isostructural with a sqc-a topological framework structure, and highly porous with the Brunauer-Emmett-Teller (BET) surface areas of 3595 and 3590 m2 g-1, respectively. Interestingly, they show intense fluorescence in water, which can be solely quenched by trace amounts of Fe3+ ions. The detection limits toward the Fe3+ ions were calculated to be 212 and 16 ppb, respectively. The efficient fluorescent quenching effect is attributed to the photoinduced electron transfer between Fe3+ ions and the ligands in these MOFs. Moreover, the introduced pyridine N donors in the ligand of BUT-15 additionally donate their lone-pair electrons to the Fe3+ ions, leading to significantly enhanced detection ability. It is also demonstrated that BUT-15 exhibits an uncompromised performance for the detection of Fe3+ ions in a simulated biological system.

A luminescent two-fold interpenetrated pillared-layer metal-organic framework for highly selective and sensitive sensing of Fe3 +

A luminescent three-dimensional metal-organic framework generally formulated as [Zn2(OH)(sip)(bpe)(H2O)]H2O (1), has been hydrothermally synthesized and characterized. It represents a new two-fold interpenetrated pillared-layer framework with (63)(69·8) topology constructed from π-electron-rich rigid ligand 5-sulfoisophthalic acid coupled with auxiliary ligand 1,2-bis(4-pyridyl)ethane. Interestingly, the strong emission of 1 could be quenched efficiently by trace amounts of Fe3+ at room temperature, even in the presence of other competing analogues, which indicated that 1 can serve as an excellent sensor for specific selective identification and quantification of Fe3+.

Solid phase extraction of heavy metals on chemically modified silica-gel with 2-(3-silylpropylimino) methyl)-5-bromophenol in food samples

Trace amounts of Fe3+, Pb2+, Cu2+, Ni2+, Co2+ and Zn2+ ions were efficiently enriched following complexation with silica-gel chemically functionalized with 2-((3-silylpropylimino)methyl)-5-bromophenol. The enriched metal ions efficiently eluted with 6 mL of 4.0 mol L−1 nitric acid and their metal contents were determined by flame atomic absorption spectrometry (FAAS). The influences of the analytical parameters and experimental variables on the recoveries of the metal ions under study were investigated and optimized. The method has high sorption preconcentration efficiency even in the presence of various interfering ions. At optimum values of all variables the method is applicable for analysis of real samples with recoveries in the range of 95 to 105% with RSD lower than 4.2% and detection limits between 1.4 and 2.8 µg L−1.

Highly Selective and Sensitized Spectrophotometric Determination of Iron (III) Following Potentiometric Study

A simple, selective and sensitized spectrophotometric method for determination of trace amounts of Fe3+ ion in tap and waste water solutions has been described. The spectrophotometric determination of Fe3+ ion using Ferron in the presence of N,N-Dodecytrimethylammonium bromide (DTAB) has been carried out. The Beer's law is obeyed over the concentration range of 0.05-2.6 microg mL(-1) of Fe3+ ion with the relative standard deviation (RSD %) <0.2% and the molar absorptivity of complexes in pH 3.5 is 3.8 x 10(3) L mol(-1) cm(-1). Potentiometric pH titration has been used for prediction of protonation constants of ferron, and evaluating its stoichiometry and respective stability constant with Fe3+ ion. As it is obvious the most likely species of ferron alone and its complexes are LH (log = 7.64), LH2 (logK = 10.52), LH3 (logK = 11.74) and ML2 (logbeta = 23.68), ML3 (logbeta = 23.68), ML3H (logbeta = 23.68), ML3H2 (logbta = 23.68) and ML(OH)2 (logbeta = 23.68) respectively.

Determination of Trace Iron in KH2PO4 Crystal by Derivative Adsorption Chronopotentiometry

A sensitive derivative adsorption chronopotentiometric method was developed to determine trace amounts of Fe3+. The influence of preconcentration time, pH of solution and constant reducing current of the peak height is discussed. The detection limit and the linear range are 5.0 × 10−10 and 2.0 × 10−9∼3.0 × 10−6 mol L−1, respectively. The method was used to determine trace Fe3+ in KH2PO4 crystals (KDP).

Extract-photometric determination of iron with 2-indolehydroxamic acid

A new extract-photometric method is proposed for determining trace amounts of Fe3+ based on the formation of a coloured complex with 2-indolehydroxamic acid (2-IHA), that can be extracted into a solution of trioctylmethylammonium chloride solution in toluene. Beer's law was obeyed between 0.06 μg/g and 1.25 μg/g (minimum error range) of iron in the aqueous phase, with a relative error (p=0.05) of ±0.86%. Molar absortivity at 455 nm was 6500 l mol−1 cm−1. The method was applied to the determination of iron in various samples: commercial pharmaceutical nutritional preparations, wine and standard samples of Portland cement and magnesite.

The catalytic properties of sugars in homogenous solutions

Different sugars catalyze the peroxydatic decoloration of indigocarmine. Trace amounts of Fe3+-ions accelerate this reaction.