Iron Ions In Aqueous Solutions Research Articles

Amphetamine-like Deferiprone and Clioquinol Derivatives as Iron Chelating Agents.

The accumulation of iron in dopaminergic neurons can cause oxidative stress and dopaminergic neuron degeneration. Iron chelation therapy may reduce dopaminergic neurodegeneration, but chelators should be targeted towards dopaminergic cells. In this work, two series of compounds based on 8-hydroxyquinoline and deferiprone, iron chelators that have amphetamine-like structures, have been designed, synthesized and characterized. Each of these compounds chelated iron ions in aqueous solution. The hydroxyquinoline-based compounds exhibited stronger iron-binding constants than those of the deferiprone derivatives. The hydroxyquinoline-based compounds also exhibited greater free radical scavenging activities compared to the deferiprone derivatives. Molecular dynamics simulations showed that the hydroxyquinoline-based compounds generally bound well within human dopamine transporter cavities. Thus, these compounds are excellent candidates for future exploration as drugs against diseases that are affected by iron-induced dopaminergic neuron damage, such as Parkinson's disease.

Unveiling the enhancement mechanism of Fe ion for muscovite flotation: Adjustment of surface potential and agent dispersion

Metal ions have been used to improve the flotation recovery of muscovite, while the enhancement mechanism is still unclear. In this paper, density functional theory (DFT) calculations and molecular dynamics (MD) simulations were employed to investigate the adsorption structure of sodium oleate (NaOL) on muscovite surface, and the diffusivity and foaming of NaOL in the pulp system, in presence of Fe3+ at different pH range. DFT calculation results suggested that the adsorption of iron ions, include FeOH2+ and Fe(OH)2+, could change the surface charge from negative to positive, thus enhancing binding performance for OL−. Moreover, MD simulations indicated that the distribution of iron ions in aqueous solution can significantly affect the dispersion of sodium oleate molecules. Specifically, FeOH2+ may lead to the complexation of oleate ions and result in the agglomeration, which is not conducive to its dispersion in solution. However, Fe(OH)2+ can significantly inhibit the aggregation of OL− molecules, and accelerate the dispersion of OL− in flotation pulp. This work reveals atomic-level mechanism of Fe ion on the dispersion and adsorption of sodium oleate in pulp, which is helpful to the understanding of minerals flotation behavior in presence of metal ions.

Selective Fluorescent Sensing for Iron in Aqueous Solution by A Novel Functionalized Pillar[5]arene.

Iron ion is one of the most physiologically important elements in metabolic processes, indispensable for all living systems. Since its excess can lead to severe diseases, new approaches for its monitoring in water samples are urgently needed to meet requirements. Here, we firstly report a novel and universal route for the synthesis of a series of pillar[n]arene derivates containing one benzoquinone unit by photocatalysis. With this in hand, an anthracene - appended water - soluble pillar[5]arene (H) with excellent fluorescence sensing potency was prepared. H enabled the ultrasensitive detection of iron ions in aqueous solution with limits of detection of 10-8 M. Over a wide range of metal ions, H exhibited specific selectivity toward Fe3+ . More importantly, H could still properly operate in a simulated sewage sample, coexisting with multiple interference ions.

Organic Luminescent Sensor for Mercury(II) and Iron(III) Ions in Aqueous Solutions

The substrate N1, N3, N5-tris(2-hydroxyphenyl)benzene-1,3,5-tricarboxamide (Sensor A) was prepared in the reaction of 1,3,5-benzenetricarboxylic acid (trimesic acid) and o-aminophenol in ethanol. The prepared organic sensor fulfills the chemiluminescent requirements including a luminophore, spacer, and suitable binding receptor that distress the probe’s luminescent features, providing selective and sensitive detection of mercury and iron ions in aqueous solutions. The sensor selectively detects mercury and iron ions in a water matrix containing various metal ions, including sodium, calcium, magnesium, zinc, and nickel. Strong and immediate binding was observed between mercury ions and the substrate at pH 7.0 with a binding affinity toward Hg2+ 9-fold higher than that observed for iron sensor binding affinity, which makes the substrate a distinctive luminescence sensor for mercury detection at ambient conditions. The sensor shows a linear response toward Hg2+ in the concentration range from 50 ppb to 100 ppm (2.0 × 10−8 to 4.2 × 10−5 M) with a limit of detection of 2 ppb (1.0 × 10−8 M). Further, Sensor A provides linear detection for iron ions in the range from 10 ppb to 1000 ppm (1.5 × 10−8 to 1.5 × 10−3 M). The measured adsorption capacity of Sensor A toward mercury ions ranged from 1.25 to 1.97 mg/g, and the removal efficiency from water samples reached 98.8% at pH 7.0. The data demonstrate that Sensor A is an excellent probe for detecting and removing mercury ions from water bodies.

Highly Sensitive Detection of Iron Ions in Aqueous Solutions Using Fluorescent Chitosan Nanoparticles Functionalized by Rhodamine B.

Detection of iron ions in aqueous solutions is of significant importance because of their important role in the environment and the human body. Herein, a fluorescent rhodamine B-functionalized chitosan nanoparticles probe is reported for the efficient detection of iron ions. The chitosan nanospheres-rhodamine B (CREN) was prepared by grafting rhodamine B onto the surface of chitosan nanospheres through an amidation reaction. The as-prepared CREN fluorescent probes exhibit high fluorescence intensity under ultraviolet light. When iron ions are added to the CREN solution, they can be coordinated with weak-field ligands such as N and O on the surface of chitosan nanoparticles (CSNP) by a high-spin method. The self-assembly of Fe3+ on the surface of the CREN led to the generation of single electrons and the presence of high paramagnetism, resulting in fluorescence quenching. The quenching effect of Fe3+ on the CREN fluorescent probe can achieve the efficient detection of Fe3+, and the detection limit reaches 10–5 mol/mL. Moreover, this fluorescence quenching effect of Fe3+ on the CREN fluorescent probe is specific, which could not be disturbed by other metal ions and counteranions.

Green synthesis of ZnO@ZnS core–shell nanoparticles for detection of lead and iron ions in aqueous solutions by colorimetric paper sensors

Green synthesis of ZnO@ZnS core–shell nanoparticles for detection of lead and iron ions in aqueous solutions by colorimetric paper sensors

Potential Advantages of Peroxoborates and Their Ester Adducts Over Hydrogen Peroxide as Therapeutic Agents in Oral Healthcare Products: Chemical/Biochemical Reactivity Considerations In Vitro, Ex Vivo And In Vivo.

Peroxides present in oral healthcare products generally exert favourable protective activities against the development and progression of tooth decay, plaque, gingivitis, and halitosis, etc. However, despite the high level of research focus on hydrogen and carbamide peroxides as therapeutically active (and tooth-whitening) agents, to date the use of alternative chemical forms of peroxides such as peroxoborates for these purposes has received only scant attention. Intriguingly, peroxoborate and its esters with polyols, such as glycerol, have a very diverse chemistry/biochemistry in aqueous solution, for which there is an increasing amount of evidence that it remains distinctive from that of hydrogen peroxide; such properties include self-associative and hydrolytic equilibria, and their abilities to participate in electrophile- or nucleophile-scavenging, metal ion-complexing, redox and free radical reactions, for example. Therefore, the purpose of this detailed commentary is to evaluate both differences and similarities between the molecular/biomolecular reactivities of peroxoborate species and hydrogen peroxide in vitro, ex-vivo and in vivo. It encompasses brief sectional accounts regarding the molecular heterogeneity of peroxoborates, the release of bioactive agents therefrom, and their oxidative attack on oral cavity biomolecules (the nucleophilic or electrophilic character of these oxidations are discussed). Further areas explored are the abilities of borates and peroxoborates to enhance the solubility of iron ions in aqueous solution, their involvements in free radical biochemistry (particularly the complexation of oxygen radical-promoting transition metal ions by, and antioxidant properties of, peroxoborate-polyol ester adducts), and the specific inhibition of protease enzymes. Further aspects focus on the tooth-whitening, oral malodor neutralizing, and potential mutagenic and genotoxic properties of peroxoborates, along with possible mechanisms for these processes. The abilities of peroxoborates, and peroxides in general, to modulate the activities of inflammatory mediators and vitamins, antioxidant or otherwise, are also explored.

In situ 3D bacterial cellulose/nitrogen-doped graphene oxide quantum dot-based membrane fluorescent probes for aggregation-induced detection of iron ions

The development of a bio-based fluorescent membrane sensor for iron ions is elaborated. A three-dimensional (3D) network structure of bacterial cellulose (BC) made by layer-by-layer in situ cultivation contained nitrogen doped graphene oxide quantum dots (N-GOQDs). The obtained BC/N-GOQDs were analyzed by SEM, TEM and XPS and demonstrated that the blue emissive N-GOQDs were homogeneously distributed in the BC mats through hydrogen bonding. These materials were found to be useful for the detection of iron ions in aqueous solutions. Experimental data showed the blue-emitting BC/N-GOQDs fluorescent probes exhibited a sensitive response to Fe3+ within a favorable concentration range of 0.5–650 μM with a very good lower limit detection of 69 nM at a signal-to-noise ratio of 3 (S/N = 3). Meanwhile, the BC/N-GOQDs–Fe3+ complexes has good reproducibility after treatment with EDTA. The quenching mechanism was attributed to strong coordination between surface functional groups (–NH2 and –OH) and Fe3+ which was successfully applied in real water samples. Diagram of quenching mechanism of the BC/N-GOQDs nanocomposites towards Fe3+ ions.

Theoretical investigations on hydrogen peroxide decomposition in aquo.

Hydrogen peroxide (H2O2) decomposition mechanisms in the absence and presence of iron ions in aqueous solution, which contain no OH radical formation, are theoretically determined. Calculating the oxygen-oxygen bond dissociation energies of H2O2, we confirmed that OH radical formation requires spin-forbidden transitions. Instead, we tested an H2O2 dimer-based decomposition mechanism and found that this mechanism provides reasonable barrier heights of 52-62 kcal mol-1, which are close to the experimental activation energy. We next calculated the oxygen-oxygen bond dissociation of H2O2 coordinating to the iron ion hydration complex in order to explore H2O2 decomposition in the presence of iron ions. Surprisingly, we found that a monovalent iron ion complex provides no reaction barrier to dissociate H2O2, in contrast to the ferrous (Fe2+) and ferric (Fe3+) ion complexes with accompanying very high barriers. Following this result, we determined the subsequent oxygen formation mechanism of the monovalent iron ion complex and found that this mechanism needs a hydrogen bond network around H2O2 to proceed at room temperature. We, therefore, conclude that H2O2 decomposition in the presence of iron ions is driven by electron transfer to the iron ion hydration complex and proceeds by hydrogen transfers in the hydrogen bond network around H2O2.

Rapid decolorization of textile wastewater by green synthesized iron nanoparticles.

The effectiveness of green tea (Camellia sinensis) and pomegranate (Punica granatum) extracts for the production of iron nanoparticles and their application for color removal from a textile industry wastewater was investigated. Polyphenols in extracts act as reducing agents for iron ions in aqueous solutions, forming iron nanoparticles. Pomegranate extract was found to have almost a 10-fold higher polyphenolic content than the same amount of green tea extract on a mass basis. However, the size of the synthesized nanoparticles did not show a correlation with the polyphenolic content. 100 ppm and 300 ppm of iron nanoparticles were evaluated in terms of color removal efficiency from a real textile wastewater sample. 300 ppm of pomegranate nanoscale zero-valent iron particles showed more than 95% color removal and almost 80% dissolved organic carbon removal. The degradation mechanisms are is considered to be adsorption and precipitation to a major extent, and mineralization to a minor extent.

Application of AMC UF membranes blended with hydrophilic CA-graft copolymer for rejection of Fe(II)/(III) ions using various ligands

Abstract Acetylated methyl cellulose (AMC) ultrafiltration (UF) membranes blended with hydrophilic cellulose acetate (CA)-based graft copolymers have been fabricated and evaluated for the removal of iron ions in aqueous solution using various ligands, Citric Acid (CiA), humic Acid (HA) and polyethyleneimine (PEI). This work shows AMC/CA-g-(GMA-g-PEG) blend membranes with improved hydrophilicity and chlorine resistance can be successfully used to remove metal ions through the formation of metal chelates. A high iron rejection (99%) was observed in the HA-Fe 2+/3+ complex ions due to strong affinity towards metal-cations than CiA-Fe 2+/3+ and PEI-Fe 2+/3+ (attained 90% rejection) for AMC blend membrane.

Comparative evaluation of five plant extracts and juices for nanoiron synthesis and application for hexavalent chromium reduction

The effectiveness of five plant extracts and juices, i.e. extracts of Camellia sinensis (green tea, GT), Syzygium aromaticum (clove, CL), Mentha spicata (spearmint, SM), Punica granatum juice (pomegranate, PG) and Red Wine (RW), for the production of nanoiron suspensions and their application for Cr(VI) reduction was investigated. Polyphenols contained in extracts act as reducing agents for iron ions in aqueous solutions, forming thus iron nanoparticles, and stabilize the nanoparticles produced from further oxidation and agglomeration. The maximum amount of polyphenols extracted per g of herbs was obtained at herb mass to water volume ratio varying from 10 to 20g/L. Suspensions of nanoparticles with sizes below 60nm were produced by mixing iron chloride solution with the plant extracts and juices investigated. The maximum concentration of nanoiron in suspensions was estimated to 22mM, obtained using RW and PG at a mixing ratio of iron solution to extract equal to 2. Lower concentrations, up to 18mM, were achieved using GT and CL extracts. Therefore, PG juice and RW were considered as more effective for nanoiron production, and, together with GT extracts, they were selected for the production of nanoiron suspensions, which have been proven effective for Cr(VI) reduction, reaching removal capacity as high as 500mg Cr(VI) per g of iron in nanoparticles.

One-Step Synthesis of Robust Amine- and Vinyl-Capped Magnetic Iron Oxide Nanoparticles for Polymer Grafting, Dye Adsorption, and Catalysis

Magnetic iron oxide nanoparticles (MIONs) bearing amine and vinyl groups are fabricated straightforwardly using vinyl-based tertiary amine molecules as both alkaline source and ligands based on the coprecipitation of iron ions in aqueous solution. The as-prepared MIONs present amphiphilic performance that can be well-dispersed both in aqueous solution and common organic solvents (e.g., ethanol, dichloromethane and tetrahydrofuran). Transmission electron microscopy (TEM), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM) measurements reveal that the MIONs are superparamagnetic Fe3O4 nanoparticles with a mean diameter below 10 nm. The presence of ligands on the surface of MIONs was confirmed by thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) characterizations. Benefiting from the surface vinyl groups, the MIONs are able to graft polyvinyl-based polymers by in situ polymerization of the corresponding vinyl monomers as confirmed by grafting poly(methyl methacrylate) (PMMA) in this paper. On the basis of their surface amine groups, the MIONs show high adsorption capacity (ca. 0.42 mmol/g) for congo red dye and excellent performance for in situ growth of Pt nanocatalyst. Moreover, the MIONs possess high stability and can be reused several times without obvious decrease of their adsorption capacity and catalytic efficiency. Considering the facile fabrication process and versatile performance of the obtained MIONs, this work may open up new opportunities for the large-scale applications of MIONs.

Study of iron(III) polymer complexes using Moessbauer spectroscopy

Metal complexes were prepared on the basis of polymer ligands with carboxylic and nitrogen-containing functionalities by complexation with iron ions in aqueous solutions of FeCl3·6H2O and FeSO4·2H2O. The degree of introduction of iron ions into the polymer matrices depended on the relative content of the functional groups in the polymers studied such as polyacrylic acid, poly-4-vinylpyridine, and poly(2-N,N-dimethylaminoethyl) methacrylate. The metal content in the polymer complexes was found to vary between 9.0 and 30.0 (for acrylic acid-based copolymers); 0.1 and 5.3 (for copolymers of 4-vinylpyridine), and 19.7 and 34.4 (for poly(2-N,N-dimethylaminoethyl) methacrylate) mg metal ions per gram of polymer carrier, respectively. An attempt was made to evaluate the structure of the Fe-containing polymeric materials by Moessbauer spectroscopy. The parameters of the Moessbauer spectra such as the isomer shift, quadrupole splitting, effective internal magnetic field, and relative weight of the partial components were consequently determined for the complexes studied at different temperatures. The results obtained proved the existence of high-spin Fe3+ ions in oxygen- or nitrogen-containing ligand environment.

Can electrospray ionization help the characterization of iron gall inks? Investigation on the interactions of gallic acid with iron ions in aqueous solutions

In the present work, an investigation has been conducted by electrospray ionization (ESI) experiments to characterize the structures of iron gall ink complexes in solution. Simple mono and polyphenolic acid molecules added to iron sulfate salts were chosen to model the recipes of ink composition. Theoretical calculations have been used (1) to determine the stability of the ionic complexes generated in the gas phase, (2) to explain which structures are more likely generated in the electrospray ion source, and (3) to determine which mechanisms are likely involved in their formation. Fragmentation pathways of the derived structures have also been investigated and rationalized to facilitate the interpretation of the data obtained under collisionally induced dissociation (CID) conditions.The present study confirms the assumption that ESI experiments with ions that are preformed in solution must be considered carefully. As a matter of fact, the study of ion formation mechanisms in the ion source is necessary to establish relationships between the ion structures in the condensed phase and the gas phase.

Catalysis of HSO3–/SO32– Oxidation by Manganese Ions

Among transition metal ions, Mn(II) ions are considered to be the most active catalysts of HSO3–/SO32– oxidation. All published data on the kinetics of the catalytic oxidation of HSO3–/SO32– by manganese ions are analyzed in this review. In addition to primary experimental data, information on the rate constants of the reactions of \({\text{SO}}_{3 - 5}^{\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{ \cdot } }\) and HSO5– with Mn(II)/Mn(III) or Fe(II)/Fe(III) ions was also engaged in this analysis. Unavoidable impurities of iron ions in aqueous solutions were found to be responsible for the observed catalytic activity of manganese ions. Manganese ions are highly efficient activators of iron ions. Manganese ions are catalytically inert in the absence of iron ions. These metal ions form a synergistic pair in which Mn(II) ions increase the catalytic properties of iron ions many times. This effect results from the catalysis of a rate-limiting step of chain propagation in sulfite oxidation and from a shift in the distribution of iron species toward Fe(III), which participates in a step of chain initiation.

Influence of mixed sulfur–nitrogen oxides on the redox kinetics of iron ions in aqueous solution

The influence of mixed sulfur–nitrogen oxides on the redox chemistry of iron-(III) and -(II) species in aqueous solution was studied kinetically as a function of various concentrations. Two oxides, viz. HONH(SO3)– and HON(SO3)22–, were found to reduce FeIII to FeII, whereby these oxides undergo an iron(III)-induced hydrolysis reaction. The hydrolysis products were analysed by ion chromatography. These redox reactions can in principle account for the inhibiting effect of sulfur–nitrogen oxides on the metal-catalysed autoxidation of sulfur(IV) oxides. Possible reaction mechanisms are suggested.

The effect of low‐temperature hydrothermal alteration on the remanent magnetization of synthetic titanomagnetites: A case for acquisition of chemical remanent magnetization

The effect of hydrothermal alteration on the thermoremanent magnetization (TRM) of synthetic titanomagnetite (TM40: Fe2.6Ti0.4O4) has been studied, to simulate the alteration that occurs in the oceanic crust. Pseudo‐single‐domain titanomagnetite grains, similar in size to those often found in oceanic basalts, were dispersed in a permeable but rigid glass matrix. This resulted in a TRM in the sample which was subsequently oxidized in acidic solutions while a magnetic field (0.1 mT) was applied perpendicular to the TRM direction. The experiments were conducted in a non‐magnetic stainless steel pressure vessel at 150°C in solutions of acidity varying from pH=2 to pH=7. In addition to being time and temperature dependent, the acquired chemical remanent magnetization (CRM) was also found to be very pH dependent. The degree of maghemitization increased drastically as the acidity of the hydrothermal solution was increased in accordance with a process controlled by the loss of iron ions in aqueous solutions. Long‐term storage experiments at carefully chosen temperatures demonstrated that no significant viscous remanent magnetization was acquired during heating. It was found that during the alteration of TM40 to titanomaghemite the CRM is along the ambient field direction from the onset, and not partly or wholly along the TRM direction as has been found in previous air oxidation experiments. This has important implications for the possible cause of anomalous skewness of marine magnetic anomalies and for the anomalous directions of natural remanent magnetization found in some oceanic basalt samples.