Soluble Iron Salts Research Articles

Iron conversion and ammonium salt calcination whitening process and mechanism of pre-calcined coal gangue

The resource utilization of coal gangue is of great significance for the reduction of bulk solid waste and the decrease of environmental risk. In this study, we changed the existence of iron-bearing substances (mainly hematite, Fe2O3) contained in the pre-calcinated coal gangue into iron sulfate (Fe2(SO4)3) by ammonium sulfate calcination. The results suggested that after being calcined with 40 % of (NH4)2SO4 at 500 °C and removing soluble iron salts (Fe2(SO4)3) by rinsing, the whiteness and specific surface area of raw coal gangue was upgraded from 38.5 % and 12.85 m2/g to 85.3 % and 34.79 m2/g, respectively, and the total amount of iron-bearing substances was reduced to 0.08 %. Moreover, the gas products obtained from the ammonium sulfate calcined coal gangue process were analyzed by simultaneous Thermogravimetry-Fourier transform infrared spectroscopy-Mass spectrometer (TG-FTIR-MS), and the main compounds released from CG860 + 40 % (NH4)2SO4 in the whole calcination process were NH3, H2O, SO, SO2, and NO.

Use of soluble iron salt as an electron acceptor to provide Fe(III) for Feammox process: Ammonium removal performance and mechanism

Fe(III) reduction coupled with anaerobic ammonium oxidation (Feammox) is a newly discovered biological ammonium removal technology. Compared to anaerobic ammonium oxidation (anammox) process, Feammox does not require NO2−-N as a reaction substrate and is more tolerant to heavy metals. In this study, soluble iron salts FeCl3 was added to anaerobic sequencing batch reactor (ASBR) to start Feammox process. The effects of Fe/N, pH and temperature on the Feammox performance were investigated. Optimal working conditions were determined by combining the variation law of nitrogen and iron elements. The results showed that the best NH4+-N removal efficiency when Fe/N, pH and temperature were 0.15, 6.5 and 30 °C, respectively. The modified Boltzmann model fitted better in Feammox kinetic analysis (R2 = 0.9789), which could clearly explain that the degradation of substrate and the generation of product. Microbial analysis showed that in addition to the typical iron-reducing bacteria, the dominant genus Candidatus_Brocadia of anammox was also enriched in the system with relative abundance of 3.16 %, implying that both Feammox and anammox contributed to the transformation of NH4+-N. Overall, optimizing the operating conditions of Feammox is important significance to maintain the stability of NH4+-N removal performance and provide theoretical basis for constructing a novel wastewater treatment process.

Stabilized Bare Superparamagnetic Iron Oxide Nanoparticles: Synthesis and Characterization

Iron is a ubiquitous element found on Earth's crust, existing in various forms, such as Magnetite (Fe3O4) and Hematite (α-Fe2O3). Magnetic iron oxide nanoparticles (MIONPs) have become increasingly popular because they possess unique properties such as high surface area to volume ratio, super-paramagnetic properties, photocatalytic properties, and economical synthesis methods. This study produced MIONPs using the co-precipitation method, stabilized by a molybdenum magnet. Two soluble iron salts (FeCl3.6H2O and FeSO4.7H2O) were reacted with 5N NH4OH solution at 80 °C in a nitrogen atmosphere. The MIONPs had a high saturation magnetization of 74.2emu/g, good crystallinity with crystalline spinel structured magnetite phase of iron oxide, high thermal stability depicted by 2.09 wt. % weight loss, and small particle sizes (6-25 nm). FTIR revealed a high-intensity peak at 546.28 cm-1, attributed to the Fe-O stretching bond. Furthermore, the study showed that the co-precipitation method could be used to produce nanoparticles with a wide range of properties that could be used for various applications. It is a promising solution for producing stabilized magnetic nanoparticles since it uses non-toxic reagents and a straightforward, secure technique. Therefore, it may be used to synthesize nanoparticles for targeted treatment, magnetic resonance imaging, drug delivery, water treatment purposes and environmental remediation.

Interaction of iron(III) with taste enhancers: Potential of Fe(III) salts with inosine monophosphate or guanosine monophosphate for food fortification

Iron interactions in iron-fortified savory concentrates lead to undesirable discoloration, even when poorly-water soluble iron salts such as ferric pyrophosphate (Fe4PP3) are used. This is the first study to comprehensively investigate the interaction of Fe(III) with three common taste enhancers: glutamate (Glu), inosine monophosphate (IMP), and guanosine monophosphate (GMP). The stability of the complexes of Fe(III) with IMP or GMP is higher compared to that with Glu. Neutrality of IMP or GMP species with Fe(III) at pH 3–8 resulted in precipitation. This property was exploited to synthesize Fe(III) salts of IMP or GMP (i.e. Fe2IMP3 and Fe2GMP3) by aqueous chemical precipitation. Iron dissolution from Fe2IMP3 and Fe2GMP3 was up to twenty-fold higher at gastric pH (1–3), indicative of better bio-accessibility, and up to fifteen-fold lower at food pH (3–7), indicative of decreased reactivity in food, compared to Fe4PP3. Consequently, Fe2IMP3 and Fe2GMP3, compared to Fe4PP3, led to less discoloration in combination with the poorly soluble phenolics that are commonly present in savory concentrates. We conclude that Fe(III) salts of IMP or GMP can potentially serve as iron fortificants due to their increased solubility at gastric pH (1–3), decreased iron dissolution at food pH (3–7), and decreased reactivity at food pH.

A Review of Gallic Acid-Mediated Fenton Processes for Degrading Emerging Pollutants and Dyes.

Diverse reducing mediators have often been used to increase the degradation of emerging pollutants (EPs) and dyes through the Fenton reaction (Fe2+ + H2O2 → Fe3+ + HO● + HO-). Adding reductants can minimize the accumulation of Fe3+ in a solution, leading to accelerated Fe2+ regeneration and the enhanced generation of reactive oxygen species, such as the HO● radical. The present study consisted in reviewing the effects of gallic acid (GA), a plant-extracted reductant, on the Fenton-based oxidation of several EPs and dyes. It was verified that the pro-oxidant effect of GA was not only reported for soluble iron salts as a catalyst (homogeneous Fenton), but also iron-containing solid materials (heterogeneous Fenton). The most common molar proportion verified in the studies was catalyst:oxidant:GA equal to 1:10-20:1. This shows that the required amount of both catalyst and GA is quite low in comparison with the oxidant, which is generally H2O2. Interestingly, GA has proven to be an effective mediator at pH values well above the ideal range of 2.5-3.0 for Fenton processes. This allows treatments to be carried out at the natural pH of the wastewater. The use of plant extracts or wood barks containing GA and other reductants is suggested to make GA-mediated Fenton processes easier to apply for treating real wastewater.

Photo-Fenton Degradation of Methyl Orange with Dunino Halloysite as a Source of Iron

The Fenton reaction is one of the most important processes for water and soil remediation, although this process has some drawbacks such as the use of H2O2 in large amounts, the formation of sludge due to the use of iron salts, and the need for acid pH values. Here we present the use of a natural clay, modified by acid treatment, as a heterogeneous catalyst to replace soluble iron salts and to avoid the use of water peroxide, resulting in a considerable increase in the attractiveness of the process. Halloysite (HT) clay from the Dunino mine consists of alumina and silica layers with the presence of iron species acting as a source of Fe ions. The etching of alumina layers using hydrochloric acid induces the release of iron species (mainly ions) in the solution, giving rise to the photodegradation activity of organic contaminants in water (i.e., Methyl Orange, MO) under UV irradiation without the need for hydrogen peroxide and avoiding the formation of sludges. MO adsorption properties and MO photodegradation ability were investigated for untreated and acid treated samples, respectively, to achieve the optimal process conditions. MO was not adsorbed on the clay’s surface due to electrostatic repulsion, but a complete degradation was observed after three hours under UV irradiation. The kinetics of photodegradation and the values of the half-life time are presented as a measure of the degradation rate. The proposed process shows a new route for effective remediation of water containing biologically active organic substances dissolved in it.

FeS2/carbon felt as an efficient electro-Fenton cathode for carbamazepine degradation and detoxification: In-depth discussion of reaction contribution and empirical kinetic model

Carbamazepine (CBZ) decay by electro-Fenton (EF) oxidation using a novel FeS2/carbon felt (CF) cathode, instead of a soluble iron salt, was studied with the aim to accelerate the reaction between H2O2 and ferrous ions, which helps to produce more hydroxyl radicals (•OH) and eliminate iron sludge. First, fabricated FeS2 and its derived cathode were characterized by scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. Anodes were then screened, with DSA (Ti/IrO2–RuO2) showing the best performance under EF oxidation regarding CBZ degradation and electrochemical characterization. Several operating parameters of this EF process, such as FeS2 loading, current density, gap between electrodes (GBE), initial [CBZ], and electrolyte type, were also investigated. Accordingly, a nonconsecutive empirical kinetic model was established to predict changes in CBZ concentration under the given operational parameters. The contribution of different oxidation types to the EF process was calculated using kinetic analysis and quenching experiments to verify the role of the FeS2-modified cathode. The reaction contributions of anodic oxidation (AO), H2O2 electrolysis (EP), and EF oxidation to CBZ removal were 12.81%, 7.41%, and 79.77%, respectively. The •OH exposure of EP and EF oxidation was calculated, confirming that •OH exposure was approximately 22.45-fold higher using FeS2-modified CF. Finally, the 19 intermediates formed by CBZ degradation were identified by ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry. Accordingly, four CBZ degradation pathways were proposed. ECOSAR software was used to assess the ecotoxicity of intermediates toward fish, daphnia, and green algae, showing that this novel EF oxidation process showed good toxicity reduction performance. A prolonged EF retention time was proposed to be necessary to obtain clean and safe water, even if the targeted compound was removed at an earlier time.

Oxidation/mineralization of AO7 by electro-Fenton process using chalcopyrite as the heterogeneous source of iron and copper catalysts with enhanced degradation activity and reusability

In the current study, the mineralization of AO7 has been studied by a novel electrochemical advanced oxidation process (EAOP) consisting of the electro-Fenton (EF) oxidation using chalcopyrite as the heterogeneous catalyst. In this process, chalcopyrite (CP) powder was employed as the source of Fe2+ and Cu2+ co-catalysts, instead of a soluble iron salt which is used in classic EF. This new process, called here as CP-EF, was able to remove 95% TOC of AO7 under an optimum experimental condition, while the removal of only 80% TOC was observed at the optimal classic EF treatments. On the other hand, a comparative study was carried out between the CP-EF and CP-PEF processes showed the superiority of heterogeneous PEF for decolorization AO7. To test the stability and reusability of our chalcopyrite based heterogeneous catalyst, leaching and cyclic experiments were carried out, based on which the catalyst was found to be reusable with a reduction of 95% in TOC removal after 6 h of electrolysis. Although both processes were effective for the treatment of AO7, the possibility of reusing the catalyst in the heterogeneous EF process justifies its economic viability in comparison with the classic electro-Fenton process. Ion chromatography analysis confirmed the release of NO3− and NH4+ ions during the AO7 mineralization.

Enhancing the ecological and operational characteristics of water treatment units at TPPs based on baromembrane technologies

The innovative baromembrane technologies for water demineralization were introduced at Russian TPPs more than 25 years ago. While being used in the power engineering industry of Russia, these technologies demonstrated certain advantages over the traditional ion-exchange and thermal technologies of makeup water treatment for steam boilers. Water treatment units based on the baromembrane technology are compact, easy to operate, and highly automated. The experience gained from the use of these units shows that their reliability depends directly on preliminary water treatment. The popular water pretreatment technology with coagulation by aluminum oxychloride proved to be inefficient during the seasonal changes of source water quality that occurs at some stations. The use of aluminum coagulant at pH 8 and higher does not ensure the stable and qualitative pretreatment regime: soluble aluminum forms slip on membranes of the ultrafiltration unit, thereby causing pollution and intoxication as well as leading to structural damages or worsening of mechanical properties of the membranes. The problem of increased pH and seasonal changes of the source water quality can be solved by substitution of the traditional coagulant into a new one. To find the most successful coagulant for water pretreatment, experiments have been performed on both qualitative and quantitative analysis of the content of natural organic matters in the Volga water and their structure. We have developed a software program and measured the concentrations of soluble aluminum and iron salts at different pH values of the source water. The analysis of the obtained results has indicated that iron sulfate at pH 6.0−10.2, in contrast to aluminum oxychloride, is not characterized by increased solubility. Thus, the basic process diagrams of water pretreatment based on baromembrane technologies with pretreatment through coagulation by iron salts and wastewater amount reducing from 60–40 to 5–2% have been introduced for thermal power stations.

Heterogeneous electro-Fenton catalyst for 1-butylpyridinium chloride degradation.

The application of the electro-Fenton process for organic compound mineralisation has been widely reported over the past years. However, operational problems related to the use of soluble iron salt as a homogeneous catalyst involve the development of novel catalysts that are able to operate in a wide pH range. For this purpose, polyvinyl alcohol-alginate beads, containing goethite as iron, were synthesised and evaluated as heterogeneous electro-Fenton catalyst for 1-butylpyridinium chloride mineralisation. The influence of catalyst dosage and pH solution on ionic liquid degradation was analysed, achieving almost total oxidation after 60min under optimal conditions (2g/L catalyst concentration and pH3). The results showed good catalyst stability and reusability, although its effectiveness decreases slightly after three successive cycles. Furthermore, a plausible mineralisation pathway was proposed based on the oxidation byproducts determined by chromatographic techniques. Finally, the Microtox® test revealed notable detoxification after treatment which demonstrates high catalyst ability for pyridinium-based ionic liquid degradation by the electro-Fenton process.

Iron oxide nanoparticles can cross plasma membranes

Iron deficiency is a major global public health problem despite decades of efforts with iron supplementation and fortification. The issue lies on the poor tolerability of the standard of care soluble iron salts, leading to non-compliance and ineffective correction of iron-deficiency anaemia. Iron nanoformulations have been proposed to fortify food and feed to address these issues. Since it was just postulated that some nanoparticles (NPs) might cross the plasma membrane also by a non-endocytotic pathway gaining direct access to the cytoplasm, we have studied iron NP uptake under this perspective. To this aim, we have used a recently tested protocol that has proven to be capable of following the cytoplasmic changes of iron concentration dynamics and we have demonstrated that iron oxide NPs, but not zerovalent iron NPs nor iron oxide NPs that were surrounded by a protein corona, can cross plasma membranes. By electrophysiology, we have also shown that a small and transient increase of membrane conductance parallels NP crossing of plasma membrane.

Cellular Iron Status Is Associated with Better Survival and Increased Chemotherapy Sensitivity in AML

Iron is mainly used in oxygen transfer reactions including reactions necessary for cellular proliferation. Since iron is essential for cellular processes, but excess iron is toxic, complex pathways have evolved to maintain iron homeostasis in various subcellular compartments. Genomic studies by others of samples in a breast cancer tissue bank have indicated that mRNA expression of iron regulatory genes predicting low iron cellular import and high iron cellular export are associated with a good prognosis, indicating that lower bioavailable cellular iron is associated with slower tumor growth rate and better patient survival. Our genomic analysis of 168 de novo AML samples reported in The Cancer Genome Atlas (TCGA) study however showed an opposite result to the breast cancer studies: 1) High iron uptake indicated by high transferrin receptor mRNA and low HFE mRNA, 2) Increased intracellular "labile" iron (bioavailable iron) indicated by low ferritin heavy chain to light chain ratio and 3) Less iron efflux indicated by low ferroportin; were all associated with significantly increased survival (p<0.02 to p<0.05). For example, 10 year overall survival was 46% for below the mean ferroportin mRNA (84 patients) vs. 20% for above the mean RNA (84 patients) (p < 0.03). Since the majority of these patients were treated with standard high dose chemotherapy, we hypothesized that increased bioavailable iron might potentiate chemotherapy effects on leukemic cells. We report in three leukemia cell lines (HL-60, BDCM, MOLM-13) the addition of soluble ferrous iron salts (50 uM, a dose reached in vivo with a single recommended IV iron dose commonly used for iron deficiency) significantly increased the growth inhibitory effect of Idarubicin (IDA) or Cytarabine (Ara-C). Growth inhibition by Ara-C or IDR was significantly increased with added iron in single experiments and was consistent; for example three consecutive experiments on separate days using MOLM-13 treated with Ara-C (1uM) or IDR (30 nM), added Fe showed significantly increased inhibition of proliferation at 24h (paired t p<0.03 for Ara-C and p<0.02 for IDR). Lower doses of chemotherapy showed more consistent results especially at later time points. For example, a relatively low dose of IDA (2.5 nM) incubated with BDCM cells caused 15% (48h) and 9% (72h) inhibition of proliferation compared to untreated cells, but with 50 uM Fe added cell counts decreased by 27% (48h) and 34% (72h), (p<0.01 compared to iron control and p<0.03 compared to treated cells with no iron added). The addition of human transferrin (100 ug/mL) to the iron containing media further increased the chemotherapy effect. FACS staining showed cells in apoptosis (annexin V positive and PI negative) were not significantly increased by the addition of iron, although there was a small consistent increase in "late" apoptosis cells (annexin V positive, PI positive) measured at 24h. Reactive oxygen species (ROS) level measured by FACS was increased in iron treated cells, supporting prior studies indicating that cells with a higher ROS levels are more sensitive to chemotherapy. Taken together these results provide strong support for further studies of iron treatment as an adjunct for chemotherapy of AML. DisclosuresNo relevant conflicts of interest to declare.

Preparation of iron bound succinylated milk protein concentrate and evaluation of its stability

Major problems associated with the fortification of soluble iron salts include chemical reactivity and incompatibility with other components. Milk protein concentrate (MPC) are able to bind significant amount of iron due to the presence of both casein and whey protein. MPC in its native state possess very poor solubility, therefore, succinylated derivatives of MPC (succ. MPC) were also used for the preparation of protein–iron complex. Preparation of the complex involved centrifugation (to remove insoluble iron), ultrafiltration (to remove unbound iron) and lyophilisation (to attain in dry form). Iron binding ability of MPC enhanced significantly (P<0.05) upon succinylation. Stability of bound iron from both varieties of complexes was monitored under different conditions encountered during processing. Higher stability (P<0.05) of bound iron was observed in succ. MPC–iron complex than native protein complex. This method could be adopted for the production of stable iron enriched protein, an organic iron source.

Preparation of succinylated sodium caseinate–iron complex by adopting ultrafiltration technology: A novel food fortificant

Abstract Iron has several functions in the human body and its deficiency leads to severe health problems. Food fortification is considered as the most acceptable strategy to combat iron deficiency, but the fortification of soluble iron salts induces many technological problems. Succinylated milk proteins can bind sufficient amount of iron. Many varieties of iron protein succinylates are also available in the market as iron supplements, not as food fortificants. Therefore, the present study was intended to prepare succinylated sodium caseinate (succ. NaCas)–iron complex suitable for food fortification purposes by adopting ultrafiltration technology. Level of iron required for the preparation of complex was standardized on the basis of maximum iron binding ability of succ. NaCas. Diafiltration carried out during the manufacturing process not only removed free iron but also reduced excess succinic acid from the complex. The obtained complex also showed better stability under different conditions encountered during processing. Industrial relevance Centrifugation and ultrafiltration (UF) technologies were adopted in the study, the former used to remove the insoluble iron and latter was used to remove free iron. The presence of both insoluble and free iron may be unacceptable for the food processing. The freeze drying technology was also used to facilitate the availability of iron protein succinylate in the powder form for wide range of food application. The proposed method will help industries to adopt the suitable conditions to produce a novel food fortificant commercially.

Complete removal of AHPS synthetic dye from water using new electro-fenton oxidation catalyzed by natural pyrite as heterogeneous catalyst

The mineralization of a new azo dye – the (4-amino-3-hydroxy-2-p-tolylazo-naphthalene-1-sulfonic acid) (AHPS) – has been studied by a novel electrochemical advanced oxidation process (EAOP), consisting in electro-Fenton (EF) oxidation, catalyzed by pyrite as the heterogeneous catalyst – the so-called ‘pyrite-EF’. This solid pyrite used as heterogeneous catalyst instead of a soluble iron salt, is the catalyst the system needs for production of hydroxyl radicals. Experiments were performed in an undivided cell equipped with a BDD anode and a commercial carbon felt cathode to electrogenerate in situ H2O2 and regenerate ferrous ions as catalyst. The effects on operating parameters, such as applied current, pyrite concentration and initial dye content, were investigated. AHPS decay and mineralization efficiencies were monitored by HPLC analyses and TOC measurements, respectively. Experimental results showed that AHPS was quickly oxidized by hydroxyl radicals (OH) produced simultaneously both on BDD surface by water discharge and in solution bulk from electrochemically assisted Fenton’s reaction with a pseudo-first-order reaction. AHPS solutions with 175mgL−1 (100mgL−1 initial TOC) content were then almost completely mineralized in 8h. Moreover, the results demonstrated that, under the same conditions, AHPS degradation by pyrite electro-Fenton process was more powerful than the conventional electro-Fenton process.

Degradation of tyrosol by a novel electro-Fenton process using pyrite as heterogeneous source of iron catalyst

Tyrosol (TY) is one of the most abundant phenolic components of olive oil mill wastewaters. Here, the degradation of synthetic aqueous solutions of 0.30 mM TY was studied by a novel heterogeneous electro-Fenton (EF) process, so-called EF-pyrite, in which pyrite powder was the source of Fe2+ catalyst instead of a soluble iron salt used in classical EF. Experiments were performed with a cell equipped with a boron-doped diamond anode and a carbon-felt cathode, where TY and its products were destroyed by hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton's reaction between Fe2+ and H2O2 generated at the cathode. Addition of 1.0 g L−1 pyrite provided an easily adjustable pH to 3.0 and an appropriate 0.20 mM Fe2+ to optimize the EF-pyrite treatment. The effect of current on mineralization rate, mineralization current efficiency and specific energy consumption was examined under comparable EF and EF-pyrite conditions. The performance of EF-pyrite was 8.6% superior at 50 mA due to self-regulation of soluble Fe2+ by pyrite. The TY decay in this process followed a pseudo-first-order kinetics. The absolute rate constant for TY hydroxylation was 3.57 × 109 M−1 s−1, as determined by the competition kinetics method. Aromatic products like 3,4-dihydroxyphenylethanol, 4-hydroxyphenylacetic acid, 4-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid and catechol, as well as o-benzoquinone, were identified by GC–MS and reversed-phase HPLC. Short-chain aliphatic carboxylic acids like maleic, glycolic, acetic, oxalic and formic were quantified by ion-exclusion HPLC. Oxalic acid was the major and most persistent product found. Based on detected intermediates, a plausible mineralization pathway for TY by EF-pyrite was proposed.

Fe‐DPA as Catalyst for Oxidation of Organic Contaminants: Evidence of Homogeneous Fenton Process

AbstractFenton‐type reactions using transition metal complexes in the decomposition of hydrogen peroxide to hydroxyl radical generation have received special attention due to their advantages over classical homogeneous processes involving soluble iron salts. Thus, the goal of this study was to investigate the use of an iron complex with the ligand pyridine‐2,6‐dicarboxylic acid (dipicolinic acid or DPA) as a homogeneous catalyst for the oxidation of the quinoline. The synthesized iron complex showed a molar ratio of 1:2 metal/ligand and was efficient in the quinoline oxidation at pH values near neutrality. The tests were monitored by mass spectrometry that allows identification of the different intermediates and showed complete oxidation of the quinolone compound. Moreover, in order to shed some light on the formation of hydroxyl radicals and the overall reaction mechanism, some theoretical calculations at the DFT level were performed. The results of this study demonstrated that the iron‐DPA complex is a good catalyst for the oxidation of quinoline by a Fenton‐like mechanism. All theoretical data show good agreement with experimental results.

Colloidal stability and chemical reactivity of complex colloids containing Fe3+

The reactivity of iron contained within insoluble colloidal metal-pyrophosphate salts was determined and compared to the reactivity of a soluble iron salt (FeCl3). As a model system for the reactivity of iron in food products, the formation of an iron–polyphenol complex was followed with spectrophotometry. Three types of systems were prepared and their colloidal stability and reactivity studied: Fe3+ pyrophosphate, protein-coated Fe3+ pyrophosphate and mixed-metal pyrophosphates containing Fe3+ and a second cation M. The additional cation used was either monovalent (sodium) or divalent (M2+). It was found that: (i) incorporating iron in a colloidal salt reduced its reactivity compared to free Fe3+ ions; (ii) coating the particles with a layer of hydrophobic protein (zein) increased stability and further decreased the reactivity. Finally, the most surprising result was that (iii) a mixed system containing more Fe3+ than M actually increased the reactivity of the contained iron, while the reverse, a system containing excess M, inhibited the reactivity completely.

Modifying Metal Nanoparticle Placement on Carbon Supports Using an Aerosol-Based Process, with Application to the Environmental Remediation of Chlorinated Hydrocarbons

A facile aerosol-based process (ABP) is developed to vary the placement of iron nanoparticles on the external surface of carbon microspheres or within the interior. This is accomplished through the competitive mechanisms of sucrose carbonization and the precipitation of soluble iron salts, in an aerosol droplet passing through a high temperature heating zone. At lower aerosolization temperatures, carbonization occurs first leading to iron salt precipitation on the external surface, while at higher temperatures interior placement occurs through concurrent iron salt precipitation and sucrose carbonization. The resulting composites are highly conducive to the reductive dechlorination of compounds such as trichloroethylene (TCE) as the carbon support is a strong adsorbent, and zerovalent iron effectively reduces TCE to innocuous gases such as ethane. Since both iron and carbon are widely used catalysts and catalyst supports, the simple process of modifying iron placement has significant potential applications in heterogeneous catalysis.

Intermolecular Enolate Heterocoupling: Scope, Mechanism, and Application

This full account presents the background on, discovery of, and extensive insight that has been gained into the oxidative intermolecular coupling of two different carbonyl species. Optimization of this process has culminated in reliable and scalable protocols for the union of amides, imides, ketones, and oxindoles using soluble copper(II) or iron(III) salts as oxidants. Extensive mechanistic studies point to a metal-chelated single-electron-transfer process in the case of copper(II), while iron(III)-based couplings appear to proceed through a non-templated heterodimerization. This work presents the most in-depth findings on the mechanism of oxidative enolate coupling to date. The scope of oxidative enolate heterocoupling is extensive (40 examples) and has been shown to be efficient even on a large scale (gram-scale or greater). Finally, the method has been applied to the total synthesis of the unsymmetrical lignan lactone (-)-bursehernin and a medicinally important 2,3-disubstituted succinate derivative.