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Graphical abstract Highlights • Very highly dispersed Pt-based catalysts were prepared by the SEA method. • Pt particles were preferentially deposited over the MOx surface. • Strong metal-support interactions existed between Pt and MO x species. • Pt/MO x /TiO 2 catalysts synthesized by SEA were evaluated during CO oxidation in presence of excess hydrogen. • A higher calcination temperature can improve the catalytic behavior of Pt/MO x /TiO 2 for the PROX reaction. Abstract In this work, the catalytic properties of Pt/MO x /TiO 2 (M = Fe, Co) catalysts prepared by strong electrostatic adsorption (SEA), were investigated for the preferential oxidation (PROX) of CO in H 2. The SEA method was chosen to achieve a preferential adsorption of Pt onto supported MO x nanoparticles rather than onto the TiO 2 surface. XPS, TPR and TEM analysis indicate that the enhancement in the catalytic activity of Pt/MO x /TiO 2 is related to a synergetic effect originated by a close contact between Pt and MO x (M = Fe, Co) surface. The results clearly show that Pt supported on CoO x /TiO 2 calcined at 300 °C, and then reduced at 100 °C, exhibits the highest activity, e.g. higher CO conversion and CO 2 selectivity, among the supported catalysts studied in this work, that was attributed to a higher concentration of Pt-CoO x moieties over the catalytic surface. This study reports a simple and efficient way to synthesize Pt-promoted catalysts where strong metal-support interactions are highly desired to improve the catalytic performance of selective oxidation reactions. [ABSTRACT FROM AUTHOR]

Abstract A mechanochemical protocol was applied to the synthesis of a magnetic material based on iron oxide nanoparticles and Al-SBA-15. Full characterization of the prepared Fe 2 O 3 /Al-SBA-15 evidenced the effective functionalization of the aluminosilicate surface. Particularly, TEM analysis revealed that the mechanochemical protocol did not considerable affect the hexagonal ordered structure of Al-SBA-15. DRIFT experiments of Fe 2 O 3 /Al-SBA-15 showed interesting acidic properties, which can be further associated to a good catalytic performance. The catalytic behavior of the prepared material was tested in the oxidation of vanillyl alcohol to vanillin, displaying an excellent activity and selectivity. The material resulted to be highly stable in the aforementioned reaction, without considerable decrease of conversion after 10 reuse cycles. Graphical abstract Unlabelled Image Highlights • Simple mechanochemical synthesis of Fe 2 O 3 /Al-SBA-15. • Efficient oxidation of vanillyl alcohol to vanillin. • Highly active oxidation catalysts (>99% conversion, 88% selectivity). • Stable mechanochemical systems with almost full initial activity after ten reuses. [ABSTRACT FROM AUTHOR]

Abstract Coal-direct chemical looping hydrogen generation (CLHG) is an innovative technology developed to produce hydrogen with in situ CO 2 capture. Most oxygen carrier (OC) candidates for other chemical looping processes are not suitable for the technology. In this work, potassium modified Fe 2 O 3 /Al 2 O 3 OCs were prepared by co-precipitation method, and screening tests were conducted to selected appropriate OC and char particle size. Experiments on the technology were carried out in a fixed bed reactor to evaluate the redox and cyclic performance of the composite OCs using Shenmu char as fuel. The OC residues in the process were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and N 2 adsorption analyzer. Moreover, the variations of potassium content in OC residues were also discussed. The results show that the appropriate particle ranges were 425 μm–600 μm for OC and less than 75 μm for char. During the first cycle, the carbon conversion could reach about more than 95% within 45 min and the total H 2 concentration under an N 2 -free basis in steam oxidation period was about 99.3%. In the multi-cycle tests, the carbon conversion and hydrogen yield remained almost unchanged during the first three cycles and decreased thereafter. The selectivity toward CO 2 was less than 80% during the first three cycles, increased in the next five cycles and reached about 99.3% in the 8th cycle. The OC exhibited a good anti-sintering ability and stable pore structure in the eight cycles. The decrease of potassium content in OCs was the reason for the decline of carbon conversion and hydrogen yield, and the supplement of K 2 CO 3 could recover the reactivity of OCs. Highlights • A new type oxygen carrier for coal-direct chemical looping hydrogen generation. • The oxygen carrier had a good anti-sintering and stable pore structure. • The total H 2 concentration under an N 2 -free basis was about 99.3%. • Potassium content in oxygen carrier was related to the reactivity of oxygen carrier. [ABSTRACT FROM AUTHOR]

Due to the widespread application of persulphate (PS) for in-situ chemical oxidation (ISCO), the PS activating role of naturally occurring minerals, such as iron oxides, has been the subject of a number of studies. However, major discrepancies remain as to the effectiveness, mode, and factors that influence iron oxides activation of PS. In this study, an attempt has been made to bridge this important knowledge gaps by a systematic study of PS activation, measured by orange G degradation, using commercial and self-synthesised magnetite, maghemite, and haematite particles. The results showed that the activation of PS by iron oxides does not depend on mineralogy, surface area or concentration of surface OH groups, but on crystalline inhomogeneities or structural irregularities. Significant dissolution of iron oxides accompanied PS activation, in a mainly homogeneous process, requiring a low pH environment to be effective. The activation of PS by iron oxides at neutral pH was found to be no better than dissolved iron activation contrary to some earlier publications. The results also suggest that under alkaline conditions, PS alone was more effective in degrading orange G than with iron oxides or dissolved iron activation. Phosphate buffer significantly retarded orange G degradation by iron-activated or unactivated PS with negative implication for ISCO in non-acidic, buffering environments. The results of this study contribute to enhancing the fundamental understanding of ISCO processes. [ABSTRACT FROM AUTHOR]

Manure-derived biogas is increasingly used at Australian piggeries to produce heat and generate electricity. However, high concentrations of hydrogen sulphide (H2S) in piggery biogas is discouraging further use, because of a lack of practical, cost-effective H2S removal options. To address this issue, on-farm trials were conducted at two piggeries. One trial tested H2S oxidation; adding small amounts of air to biogas, upstream of a low-cost enhanced surface treatment vessel which was fabricated on-farm with intrinsic safety measures. Covered anaerobic pond (CAP) effluent provided a convenient, low-cost nutrient source for the biofilm of naturally-occurring microorganisms in the packed column. This treatment was effective, removing over 90% of the H2S in a single pass and reducing H2S concentrations from 4000 ppm to <400 ppm. Another trial tested chemisorption performance of natural, iron-rich red soil, mixed with a ground sugar cane mulch bulking agent, in comparison with cg5 commercial media (iron-oxide pellets). The red soil removed H2S, but had a substantially lower capacity (∼2 g S/kg red soil) than the cg5 (∼200 g S/kg media). Accordingly, red soil is unlikely to be feasible as a primary treatment medium, but may be useful for final polishing after an oxidation step has removed most of the H2S. [ABSTRACT FROM AUTHOR]

Currently, considerable effort is being made towards synthesis and characterization of iron oxide nanoparticles. In this article, we report on the preparation and characterization of iron oxide nanoparticle (NP) arrays supported on natively oxidized Si(100) surface. The NPs are synthesized by reverse micelle nanolithography technique and are then deposited onto natively oxidized Si(100) surface via spin-coating. Plasma oxidation followed by high temperature annealing results in a unimodal size distribution of pseudohexagonally-ordered array of iron oxide NPs (with ∼14 nm mean diameter and ∼5 nm mean height). High temperature annealing does not fragment the NPs. Particles are sinter-resistant: the unimodal arrays are robust with respect to thermal treatment. X-ray absorption spectroscopy (XAS), including X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS), reveals that structure of the iron oxide particle resembles closely the hematite α-Fe 2 O 3 structure. Furthermore, with the help of EXAFS spectra, we eliminate the possibility of γ-Fe 2 O 3 , Fe 3 O 4 , FeO and FeO(OH) structures for the NPs. [ABSTRACT FROM AUTHOR]

α-Fe 2 O 3 catalyst supported on rice husk ash (RHA) with enhanced photochemical NO oxidation is reported. The Fe 2 O 3 /SiO 2 composites are prepared through the calcination of RH and FeCl 3 at temperatures of 600 and 900 °C, during 1 and 4 h. Fe 2 O 3 crystalizes covering the cob-shaped silica skeleton. The thermal procedure determines the mineralogical composition, crystalline growth and surface area of samples. Samples obtained at 600 °C are α-Fe 2 O 3 (hematite) with low levels of Fe 2 SiO 4 and exhibit a microstructure constituted of meso/macropores, with surface area values of 19.6 and 16.1 m 2 g −1 . At 900 °C only pure hematite is obtained but the microstructure is denser with very small surface area. Increasing the time of calcination to 4 h, hexagonal plates and truncated pseudocubes large crystals are obtained. All the samples exhibit light absorption in the 300 to 900 nm UV–vis range. The photocatalytic oxidation of NO molecules is related to the surface area of the samples. In the best case an NO conversion value of 24% is found, the highest reported for hematite photocatalysts. Moreover, the selectivity of NO → NO 2 → NO 3 − oxidation process reaches values as high as 72% with the presence of large hexagonal plate hematite crystals. The existence of particles, which exhibit {001} facets, favors the adsorption of NO 2 molecules and, therefore, the achievement of the photochemical oxidation process. [ABSTRACT FROM AUTHOR]

This study reports on the synthesis of a novel composite Fe-N/O catalyst for the enhancement of oxidative capacity of persulfate at ambient temperature. The fabricated composite was characterized by XRD, FTIR and TEM techniques. Results showed that the composite Fe-N/O catalyst consist of Fe3N and Fe3O4 crystal phases. The performance of Fe-N/O in the oxidation of Acid Red 73 (AR 73) by persulfate was investigated and it was found that the decolorization efficiency and total organic carbon removal (TOC) were 96% and 72.5% in 10 min at 22 °C, respectively. It was concluded that the interface between the Fe3N and Fe3O4 phases might account for the high efficiency observed. [ABSTRACT FROM AUTHOR]

In order to contribute to the environment preservation, catalysts based on iron oxides supported on activated carbon were prepared from peanut hulls and evaluated in Fenton reaction to remove methylene blue from model wastewaters. The activated carbons were prepared by simultaneous carbonization and activation of peanut hulls with low amounts of sodium hydroxide and then impregnated with iron nitrate solutions to get samples with 5, 7.5,10, 12.5 and 15 wt.% Fe. All solids were microporous and made of hematite and magnetite supported on activated carbon. The amount of magnetite changed with iron content and was related to surface oxidation, producing more oxygenated groups (carboxylic acids, lactones, carboxylic anhydrides and phenols) than activated carbon. Both activated carbons and iron-based catalysts were able to remove methylene blue from aqueous streams by adsorption and oxidation, the activity of activated carbon being assigned to oxygenated groups. For iron oxide-based catalysts, the adsorption capacity was related to the increase of surface oxygenated groups while the oxidation activity was assigned to the amount and crystals size of magnetite, besides the surface oxygenated groups. The association of these properties led to catalysts with close performances, being the catalyst with 10 wt.% Fe slightly more efficient than the others in dye removal. The obtained catalysts produced low amounts of byproducts, being promising to remove dyes in industrial wastewaters. In addition, they have the advantage of being prepared with less sodium hydroxide than the traditional preparations, decreasing the amount of wash water, besides reducing the amounts of peanut hulls disposed in the environment. [ABSTRACT FROM AUTHOR]

Preparation and use of an iron containing catalyst, Fe 2 O 3 modified kaolin (Fe 2 O 3 -KLN), was investigated to develop a heterogeneous electro-Fenton process for the electrochemical oxidation of enoxacin (ENXN). The characterizations of the prepared Fe 2 O 3 -KLN were performed using different methods. Mineralization efficiency of the electro-Fenton method increased in the presence of Fe 2 O 3 -KLN catalyst. The experimental variables that affect the efficiency of heterogeneous electro-Fenton treatment were investigated. Mineralization rates of ENXN reached its maximal value in the presence of 0.3 g Fe 2 O 3 -KLN at 300 mA. While the mineralization efficiency of ENXN was much higher in pH values of 2.0 and 3.0, the total mineralization of ENXN was also observed at pH values of 5.1 and 7.1. A very small decrease (0.5%) was found in the activity of Fe 2 O 3 -KLN after five runs. Characterization studies showed that the change in the morphology and chemical structure of Fe 2 O 3 -KLN during the experiments was negligible. The amount of leached iron (∼0.006 mM) revealed that hydroxyl radicals were mainly produced by heterogeneous reactions of surface iron species. GC–MS, HPLC and LC–MS analysis allowed the identification of some of organic oxidation intermediates. Inorganic oxidation intermediates (F − , NO 3 − and NH 4 + ) were identified by IC analysis. An oxidation pathway was proposed for the mineralization of ENXN. [ABSTRACT FROM AUTHOR]

The novel iron-oxide based glass-fiber catalysts (GFC) for the H 2 S selective oxidation uses the support in form of the glass microfibrous fabric, premodified by external layer of secondary porous SiO 2 support. The specific activity of FeOx-SiO 2 /GFC catalyst per unit mass of active component exceeds that of the similar conventional Fe 2 O 3 /Al 2 O 3 catalyst by more than an order of magnitude due to the more dispersed state of active component in the GFC (1–2 nm compared to 15–30 nm in conventional catalyst). The proposed GFC also looks advantageous in terms of mass transfer efficiency and easy scale-up. [ABSTRACT FROM AUTHOR]

Using high-resolution scanning tunneling microscopy (STM) we have studied the oxidation of ultrathin FeO films grown on Pt(111). At the initial stage of the FeO film oxidation by atomic oxygen exposure, we identified three distinct types of line defects, all of which form boundaries between FeO domains of opposite orientation. Two types of line defects appearing bright ( type-i ) and dark ( type-ii ) in the STM images at typical scanning parameters are “metallic”, whereas the third line defect exhibits nonmetallic behavior ( type-iii ). Atomic-scale structure models of these line defects are proposed, with type-i defects exhibiting 4-fold coordinated Fe atoms, type-ii exhibiting 2-fold coordinated O atoms, and type-iii exhibiting tetrahedrally-coordinated Fe atoms. In addition, FeO 2 trilayer islands are formed upon oxidation, which appear at FCC-type domains of the moiré structure. At high scanning bias, distinct protrusions on the trilayer islands are observed over surface O ions, which are assigned to H adatoms. The experimental data are supported by density functional theory (DFT) calculations, in which bare and hydroxylated FeO 2 trilayer islands are compared. Finally, we compare the formation of O-rich features on continuous FeO films using atomic oxygen with the oxidation of Pt(111)-supported FeO islands accomplished by O 2 exposure. [ABSTRACT FROM AUTHOR]

The influence of iron oxide, FeO x , on Pt for CO oxidation was investigated. A film of FeO x , nominally 0.8-nm thick, was added to a Pt/Al 2 O 3 catalyst by Atomic Layer Deposition. The film was found to wet the Pt surface after oxidation at 773 K and 973 K, as shown by aberration-corrected, transmission electron microscopy. In-situ infrared spectra and CO chemisorption measurements showed that the addition of the FeO x greatly suppressed CO adsorption but enhanced CO oxidation rates due to FeO x -Pt interfaces. The FeO x layer also improved the stability of the catalyst by mitigating the sintering of Pt particles at 973 K. • Atomic-scale FeO x overlayer augments the CO oxidation activity and thermal stability of the Pt/Al 2 O 3 at 973 K. • TEM and CO chemisorption shows that FeO x overlayer wets the Pt surface and greatly suppresses CO adsorption on Pt. • In-situ infrared spectra shows that CO oxidation occurs without CO adsorption on FeO x -overcoated Pt catalyst. • FeO x overlayers near Pt enhances CO oxidation rates through the FeO x -Pt interfaces. [ABSTRACT FROM AUTHOR]

Thermal oxidation of iron foil was done at 400 °C and 500 °C in for 2 h to form multilayered oxide scale with outer oxide layer of α-Fe 2 O 3 comprising of nanowires and nanosheets respectively. Iron oxidized at 300 °C formed a rather compact film with no noticeable nanostructures. The morphologies of oxide formed in different oxidation environment (water vapour or dry air) were compared; densely packed nanostructures were produced in water vapour compared to dry air. Time variation study indicated rapid growth of nanostructure whereby for 1 min at 500 °C dense nanowires with some noticeable nanosheets were already observed. The nanowires and nanosheets were used to adsorb Cr(VI) from aqueous solution. Adsorption of 10 ppm of Cr(VI) on the nanowires and nanosheets was found to be successful with much faster removal efficiency for the nanosheets. Both samples displayed complete adsorption for less than 1 h. [ABSTRACT FROM AUTHOR]

Iron oxide produced by iron-oxidizing bacteria, Leptothrix ochracea , ( L -BIOX) obtained from a freshwater purification plant, Joyo City in Kyoto, Japan catalyzed Baeyer-Villiger oxidation with molecular oxygen in the presence of benzaldehyde at 25 °C more efficiently than usual iron compounds. L -BIOX can promote the reactions of various substrates to give the desired products in sufficient yields and was found to be reusable. Scanning transmission electron microscopy and 57 Fe Mössbauer spectroscopy revealed that no change of the surface structure of L -BIOX was observed even after four times of the recycling test and the oxidation state of iron in L -BIOX is trivalent before and after the oxidation of cyclohexanone. An investigation with analogous amorphous iron oxides which contain silicon revealed that the catalytic activity of L -BIOX might stem from a synergetic effect of iron and silicon in the structure. [ABSTRACT FROM AUTHOR]

Synopsis The control rod of a light water nuclear reactor is constructed of a pole comprising stainless steel filled with a boron carbide (B 4 C) core. To appraise the stability of this control rod in the event of a severe accident, the reactions of the system of B 4 C and grade 304 austenitic stainless steel (SS) were observed at 1473 K in Ar, air, and a mixture of both. To clarify the reaction mechanism and the influence of the oxygen partial pressure, the weight change ratio was monitored and differential thermal analysis was performed at the temperature range from room temperature to 1673 K to monitor the reaction under controlled oxygen partial pressure. The results showed that there was no direct reaction between B 4 C and SS. When the temperature was higher than the melting point of B 2 O 3 (743 K), the molten B 2 O 3 formed by oxidation of B 4 C covered the surface of SS by spreading wetting. This B 2 O 3 layer functioned to transport oxygen from the atmosphere to SS, leading to accelerated oxidation of SS. As a result, a Fe–Cr–Ni–B–O oxide phase covered the surface of SS. Oxygen continuously entered the oxide phase with prolonged reaction time, and oxides such as Fe 2 O 3 , Fe 3 O 4 , and FeOx–Cr 2 O 3 were found on the outer layer. Therefore, in the presence of B 2 O 3 formed by oxidation of B 4 C, the oxidation of SS was accelerated below the eutectic temperature of the Fe–C system. [ABSTRACT FROM AUTHOR]

Iron-based hydrotalcite catalysts such as MnFe, CoFe, CeFe, NiFe and MgFe as well as their single monoxides were screened for selective oxidation of styrene to obtain benzaldehyde and styrene epoxide. The catalysts were characterized by X-ray diffraction, ATR-FTIR and Raman spectroscopy, chemical analyses, scanning electron microscopy coupled to EDX and N 2 adsorption–desorption measurements, before and after the catalytic evaluation. The influence of the reaction conditions such as temperature, reactant compositions as well as the presence of solvents was also evaluated. Best performances were reached by MnFe due to the presence of α-Fe 2 O 3 and γ-Fe 2 O 3 phases together with the stable MnFe 2 O 4 one. These species allowed reaching 17% of styrene conversion and selectively produced benzaldehyde and styrene epoxide, after 72 h of reaction. Under these conditions, MnFe can be recycled by 3 times with a very low deactivation rate due to the partial loss of catalyst structure, after being characterized by Raman and ATR-FTIR. [ABSTRACT FROM AUTHOR]

The use of iron oxides as materials for advanced oxidation processes has been widely reported, however the hematite phase has been poorly studied. Catalytic cycles show the importance of the redox states of the Fe 2+ /Fe 3+ , although hematite has only Fe 3+ . The introduction of dopant ion, such as 3% niobium in the hematite structure, is able to make it an effective material for treatment of polluted water. In our work it was possible to verify a removal of approximately 45% of a methylene blue (MB) solution (10 mg L −1 ) using Nb-doped hematite and 75% of the same MB solution using the oxide after a previous treatment with H 2 O 2 to generate surface peroxo groups. [ABSTRACT FROM AUTHOR]

Abstract: Iron clusters produced in a laser vaporization source were deposited to form cluster-assembled thin films with different thicknesses on highly oriented pyrolytic graphite substrates. The development of oxidation of the clusters with time, up to three years, was investigated by magnetic measurements using an alternating gradient magnetometer. Furthermore, to receive information about the oxidation states, clusters of 57Fe were studied using Mössbauer spectroscopy. The magnetic analysis shows a time evolution of the saturation magnetization, remanence, and coercivity, determined from the hysteresis curves characteristic of a progressing oxidation. The different thicknesses of the iron cluster films as well as a protective layer of vanadium influence the magnetic properties when the samples are subjected to oxidation with time. While the saturation magnetization and remanence decrease and reach half the initial values for almost all the samples after three years, the coercivity increases for all samples and is more substantial for the thickest sample with a vanadium protective layer. This value is three folded after three years. Furthermore, based on a core–shell model and using the saturation magnetization values we have been able to quantitatively calculate the amount of the increase of Fe-oxide as a function of time. The Mössbauer spectroscopy shows peaks corresponding to iron metal and maghemite. [Copyright &y& Elsevier]

Highlights: [•] Development of efficient catalysts for both WGS and PrOx reactions. [•] Extensive study of the PrOx reaction parameters to achieve the best activity/selectivity ratio. [•] CO/H2 pulses study for understanding of H2/CO oxidation competition. [•] Suitability of the samples in the PrOx reaction especially under high CO inlet concentrations. [ABSTRACT FROM AUTHOR]

Abstract: Corrosion resistance of iron oxides on iron foils prepared by anodization, annealing or a combination of both was characterized by electrochemical methods. Even though iron oxide film with a thickness of more than 2μm could be prepared by single anodization, corrosion resistance deteriorated because the oxide film was in the amorphous phase and contained many defects. Corrosion resistance of iron oxides was also not enhanced by single annealing. Conversely, combination of anodization and subsequent annealing led to a positive shift of the corrosion potential in the Tafel plot, indicating that corrosion resistance was improved. Formation of thicker oxide during anodization was associated with a more positive shift in corrosion potential after annealing. Electrochemical impedance spectroscopy showed that the slowest charge transfer was observed in oxide films grown by a combination of anodization and annealing. We found that the optimum annealing temperature of anodic films in terms of the most positive shift of E corr was 500°C. [Copyright &y& Elsevier]

Highlights: [•] Schwertmannite was found to be a promising Fenton-like catalyst in the oxidation of phenol. [•] H2O2 decomposition catalyzed by schwertmannite was via a OH radical mechanism. [•] OH produced at pH 3.0 was mainly through the catalytic mechanism of dissolved Fe(III). [•] OH produced at pH 5.0 was mainly through the catalytic mechanism of Fe(III) species. [•] Schwertmannite showed a high saline-tolerance and a good reusability in the oxidation of phenol. [Copyright &y& Elsevier]

Highlights: [•] Patterning of thin spinel ferrite films by a low power laser spot is demonstrated. [•] Hollow or raised zones can be created by low power laser heating, according to the elaboration conditions of the films. [•] Local phase change or oxidation can be induced by a laser spot in a spinel ferrite film. [•] Magneto-photonic or magnonic crystals can be prepared by direct laser irradiation of spinel ferrite thin films. [Copyright &y& Elsevier]

Abstract: 2,2,3,3-Tetrafluoro-1-propanol (TFP, C3H4F4O, M.W. = 132.06) is extensively used as the solvent in CD-R and DVD-R fabrication. Since it has a fluorinated alky-chain configuration and is non-biodegradable, its treatment by conventional oxidation methods is typically very inefficient. In this work, novel three-phase fluidized bed reactor (3P-FBR, 7.5 cm in diameter, 50 cm high) that combines photo oxidation (UV/H2O2, one of AOPs (Advanced Oxidation Process) and adsorption (BT5 iron oxide as adsorbent) processes is designed for mineralizing and defluorinizing TFP wastewater. The experimental results reveal that TFP can be efficiently mineralized, and the BT5 that is circulated by aeration in the 3P-FBR system can remove the released fluoride ions in the reaction period. Irradiation with 254 nm UV and a 10 mM H2O2 dose yield a TOC removal of TFP (1.39 mM, equivalent to an initial TOC of 50 ppm) of over 99.95% in 2 h, and 99% of fluoride was removed by BT5 with an adsorption capacity of 24.1 mg-F g−1. [Copyright &y& Elsevier]

Abstract: Different iron oxide structures were formed by annealing of iron foils in air at temperatures between 500°C to 800°C. Depending on temperature, a significant variation in the hematite/magnetite ratio and a strongly temperature dependent morphology is obtained. While over a wide range of conditions more or less compact Fe3O4/Fe2O3 layers are obtained, at 600°C rapid growth (several micrometer per hour) of highly crystalline hematite nanowires can be observed. Visible light photocurrent measurements in 1M NaOH under AM 1.5 100mW/cm2 conditions show that photocurrent density and the onset potential for water oxidation strongly shifted in the cathodic direction for the nanowire morphology. The results indicate that a simple air oxidation of iron can provide a rapid path to form hematite nanowires. Obtained layers are considerably active as photoanodes for solar water splitting. [Copyright &y& Elsevier]

Abstract: Thermally oxidized iron oxide (α-Fe2O3, Hematite) nanostructures are investigated as photoanodes that convert solar energy into hydrogen by splitting water. α-Fe2O3 is stable for water photo-oxidation, it has a favorable band gap energy and is a non-toxic common material. However, α-Fe2O3 photoanodes suffer from high loss due to electron-hole recombination; therefore nanoarchitectures with high aspect ratio that allows photons to be absorbed close to the photoanode/electrolyte interface are preferred. The thermal oxidation of iron is a simple way to produce nanostructured iron oxide electrodes. Different morphologies, aspect ratios, and oxide thicknesses result depending on the process parameters. Nanorod structures were obtained by annealing iron foils in oxygen rich atmosphere, whereas annealing in oxygen lean atmosphere resulted in nanocoral-like morphology. The nanorod-structured photoanodes achieved moderate photocurrent density of 0.9 mA/cm2 while the nanocoral morphology achieved 2.6 mA/cm2 (both at 1.8 V vs. the reversible hydrogen electrode). The effect of the oxidation process and oxide layer on performance is discussed. [Copyright &y& Elsevier]

Abstract: Reduction of metal oxide oxygen carrier has been attractive for direct CO oxidation and CO2 separation. To investigate the reduction behaviors of iron oxide prepared by supporting Fe2O3 on γ-Al2O3 and its effect on CO oxidation, fluidized-bed combustion experiments, thermogravimetric analyzer (TGA) experiments, and density functional theory (DFT) calculations were carried out. Gas yield increases significantly with the increase of temperature from 693K to 1203K, while carbon deposition decreases with the increase of temperature from 743K to 1203K, where temperature is a very important factor for CO oxidation by iron oxide. Further, it were quantitatively detected that the interaction between CO and Fe2O3, breakage of O–Fe bonds and formation of new C–O bonds, and effect of reduction degree were quantitatively detected. Based on adsorptions under different temperatures and reducing processes from Fe3+ into Fe2+, Fe+ and then into Fe, it was found that Fe2+ →Fe+ was the reaction-controlling step and the high oxidation state of iron is active for CO oxidation, where efficient partial reduction of Fe2O3 into FeO rather than complete reduction into iron may be more energy-saving for CO oxidation. [Copyright &y& Elsevier]

Abstract: In the water treatment field, activated carbons (ACs) have wide applications in adsorptions. However, the applications are limited by difficulties encountered in separation and regeneration processes. Here, activated carbon/Fe3O4 nanoparticle composites, which combine the adsorption features of powdered activated carbon (PAC) with the magnetic and excellent catalytic properties of Fe3O4 nanoparticles, were fabricated by a modified impregnation method using HNO3 as the carbon modifying agent. The obtained composites were characterized by X-ray diffraction, scanning and transmission electron microscopy, nitrogen adsorption isotherms and vibrating sample magnetometer. Their performance for methyl orange (MO) removal by adsorption was evaluated. The regeneration of the composite and PAC-HNO3 (powdered activated carbon modified by HNO3) adsorbed MO by hydrogen peroxide was investigated. The composites had a high specific surface area and porosity and a superparamagnetic property that shows they can be manipulated by an external magnetic field. Adsorption experiments showed that the MO sorption process on the composites followed pseudo-second order kinetic model and the adsorption isotherm date could be simulated with both the Freundlich and Langmuir models. The regeneration indicated that the presence of the Fe3O4 nanoparticles is important for a achieving high regeneration efficiency by hydrogen peroxide. [Copyright &y& Elsevier]

Abstract: The mechanisms of iron precipitation and crystallization in a fluidized-bed reactor were investigated. Within the typical Fenton’s reagent dosage and pH range, ferric ions as a product from ferrous ion oxidation would be supersaturated and would subsequently precipitate out in the form of ferric hydroxide after the initiation of the Fenton reaction. These precipitates would simultaneously crystallize onto solid particles in a fluidized-bed Fenton reactor if the precipitation proceeded toward heterogeneous nucleation. The heterogeneous crystallization rate was controlled by the fluidized material type and the aging/ripening period of the crystallites. Iron crystallization onto the construction sand was faster than onto SiO2, although the iron removal efficiencies at 180 min, which was principally controlled by iron hydroxide solubility, were comparable. To achieve a high iron removal rate, fluidized materials have to be present at the beginning of the Fenton reaction. Organic intermediates that can form ferro-complexes, particularly volatile fatty acids, can significantly increase ferric ion solubility, hence reducing the crystallization performance. Therefore, the fluidized-bed Fenton process will achieve exceptional performance with respect to both organic pollutant removal and iron removal if it is operated with the goal of complete mineralization. Crystallized iron on the fluidized media could slightly retard the successive crystallization rate; thus, it is necessary to continuously replace a portion of the iron-coated bed with fresh media to maintain iron removal performance. The iron-coated construction sand also had a catalytic property, though was less than those of commercial goethite. [Copyright &y& Elsevier]

Abstract: A low-temperature catalytic oxidation of chlorobenzene (CB) has been performed at temperatures of 60–210°C using ozone (O3) over iron oxide and manganese oxide, respectively. In the absence of ozone, CB conversion achieved with these two catalysts at 200°C was below 10%. However, addition of 1200ppm ozone results in a remarkable increase in CB conversion and the conversion reaches 91.7% at 150°C for iron oxide, while 81.5% conversion is achieved with manganese oxide at 90°C. The activation energy of manganese oxide (48kJmol−1) is higher than that of iron oxide (43kJmol−1) without ozone. However, as ozone is added, the activation energy is significantly reduced to 20.0kJmol−1 for iron oxide. CO and CO2 are the only carbon-containing products detected in the effluent gas stream. For the long-term test, no obvious deactivation was found in iron oxide and ozone. However, in the case of manganese oxide and ozone, 3% reduction of CB conversion was observed. Slight deactivation might be attributed to a small amount of reaction byproducts (carboxylic acid species) and residual chloride (MnCl2) being deposited on the active sites of the catalysts. [Copyright &y& Elsevier]

Abstract: In this study, we examined the experimental catalytic oxidation of gaseous monochlorobenzene (MCBz) with O3 over Fe2O3 in a packed bed reactor to investigate the feasibility of economical low temperature decomposition at a high space velocity (SV). We investigated the effects of several reaction parameters (temperature, O3 concentration, and SV) on the MCBz oxidation. At 150°C, the conversion of MCBz over Fe2O3 in the absence of O3 was only 3%; it increased to 91% over Fe2O3 in the presence of 1200ppm of O3 at a high SV of 83s−1. A long-term operation study revealed that the conversion of MCBz was stable for more than 96h. In the steady state, the carbon and chlorine balances were 88% and 86%, respectively. Applying a Langmuir–Hinshelwood kinetic model, we estimated an activation energy of 16.7kJmol−1 for MCBz oxidation over Fe2O3 in the presence of O3. [ABSTRACT FROM AUTHOR]

Abstract: A chemical looping process using the redox reactions of iron oxide has been used to produce separate streams of pure H2 and CO2 from a solid fuel. An iron oxide carrier prepared using a mechanical mixing technique and comprised of 100wt.% Fe2O3 was used. It was demonstrated that hydrogen can be produced from three representative coals – a Russian bituminous, a German lignite and a UK sub-bituminous coal. Depending on the fuel, pure H2 with [CO] ≲50vol.ppm can be obtained from the proposed process. The cyclic stability of the iron oxide carrier was not adversely affected by contaminants found in syngas which are gaseous above 273K. Stable quantities of H2 were produced over five cycles for all three coals investigated. Independent of the fuel, SO2 was not formed during the oxidation with steam, i.e. the produced H2 was not contaminated with SO2. Since oxidation with air removes contaminants and generates useful heat and pure N2 for purging, it should be included in the operating cycle. Overall, it was demonstrated that the proposed process may be an attractive approach to upgrade crude syngas produced by the gasification of low-rank coals to pure H2, representing a substantial increase in calorific value, whilst simultaneous capturing CO2, a greenhouse gas. [Copyright &y& Elsevier]

Abstract: Two samples of heterogeneous catalysts were prepared by impregnating a raw-clay, a montmorillonite-rich material, with iron oxides, in order to be used in oxidative reactions of toluene. The starting clay-sample was collected from a pedon in the region of San Juan, Argentina. All catalysts were characterized with X-ray powder diffraction (XRD), infrared spectroscopy, temperature programmed reduction (TPR), scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDS), and specific surface area measurements. After impregnating the raw clay material with iron oxides, there was a collapse of basal plane spacing and an increase in surface area, from 17 to 62m2 g−1 of montmorillonite. The TPR, EDS, and XRD results evidenced that the dispersion of iron-containing species depended on how the impregnation was made. The catalyst with higher exposure to iron oxides on sample preparation presented a higher catalytic activity on toluene oxidation. [Copyright &y& Elsevier]

Abstract: The reuse of iron oxide nanoparticles as a catalyst of organic matter in the H2O2/iron oxide mineralization process was investigated. The particle size and morphology of iron oxide particles obtained from TEM (Transmission Electron Microscopy) images and DLS (Dynamic Light Scattering) measurements, indicate the formation of a rod-like morphology with an average length of 50±10nm. An electron diffraction pattern identified the particles as either α-FeOOH or β-FeOOH. Stability of iron oxide nanoparticles in organic model compound solutions was studied as a function of pH solution and was correlated with average size. The optimal pH for maximum mineralization in the H2O2/iron oxide system was found to be 2.8. Finally, results indicated that at least seven stages of catalytic mineralization-recovery cycles can take place without a reduction in the catalytic properties of the iron oxide nanocatalyst. [ABSTRACT FROM AUTHOR]

Abstract: In the present paper, effect of iron on activity of catalyst CuO/CeO2 in selective CO oxidation in H2-containing gases mixture was investigated. Catalysts were prepared by wet impregnation and calcination at 400°C, characterized by ICP, BET, H2-TPR, XRD and TEM. The addition of iron to Cu/CeO2 catalyst improved the catalytic activity and selectivity for CO oxidation. Discussion of the results showed that the synergistic effect is correlated to better reducibility and dispersion of copper in the presence of the iron metal additive. [ABSTRACT FROM AUTHOR]

Abstract: Temperature programmed desorption (TPD), electron energy loss spectroscopy (ELS) and low energy electron diffraction (LEED) were used to study the interaction of molecular oxygen with the (2×1) reconstructed surface of hematite α-Fe2O3(011­2) under UHV conditions. The (2×1) surface is formed from vacuum annealing of the ‘ideal’ (1×1) surface and possesses Fe2+ surface sites based on ELS. While O2 does not stick to the (1×1) surface at 120K, the amount of O2 that can be reversibly adsorbed at 120K on the (2×1) surface was estimated to be ∼0.5 ML (where 1 ML is defined as the Fe3+ surface coverage on the ideal (1×1) surface), with additional O2 that is irreversibly adsorbed based on subsequent H2O TPD. Molecularly and dissociatively adsorbed O2 modifies the surface chemistry of H2O both in terms of enhanced OH stability (relative to either the (1×1) or (2×1) surfaces) and in the blocking of H2O adsorption sites. While O2 adsorption at 120 to 300K does not transform the (2×1) surface into the (1×1) surface, the influence of O2 on the (2×1) surface involves both charge transfer from surface Fe2+ sites and formation of an ordered c(2×2) structure resulting from O2 dissociation. [Copyright &y& Elsevier]

Abstract: Particle size distributions from a series of experiments involving the photo-oxidation of iron pentacarbonyl [Fe(CO)5] in ozone at atmospheric pressure and 295K are reported for a range of initial reactant concentrations, varying photolysis rates and particle growth times. These data sets were used to test a model which describes the formation of FeO3 in the gas phase, followed by clustering to produce primary Fe2O3 particles. These subsequently coagulate to form fractal-like structures as a result of magnetic dipole coupling of the primary particles. For the smallest size, spherical particles, Smoluchowski theory was used to determine a coagulation constant (kS ) of 7.0×10−10 cm3 s−1, indicating a primary particle diameter of 6.6nm, in very good agreement with the optimised value used in the particle growth model for this system. Finally, these findings are used in discussion of the formation and growth of Fe2O3 ‘meteoric smoke’ particles in the upper atmosphere. [Copyright &y& Elsevier]

Abstract: Iron oxide nanoparticles of reduced oxidation state, mainly in the form of magnetite, have been synthesized utilizing a new continuous, gas-phase, nonpremixed flame method using hydrocarbon fuels. This method takes advantage of the characteristics of the inverse flame, which is produced by injection of oxidizer into a surrounding flow of fuel. Unlike traditional flame methods, this configuration allows for the iron particle formation to be maintained in a more reducing environment. The effects of flame temperature, oxygen-enrichment and fuel dilution (i.e. the stoichiometric mixture fraction), and fuel composition on particle size, Fe oxidation state, and magnetic properties are evaluated and discussed. The crystallite size, Fe(II) fraction, and saturation magnetization were all found to increase with flame temperature. Flames of methane and ethylene were used, and the use of ethylene resulted in particles containing metallic Fe(0), in addition to magnetite, while no Fe(0) was present in samples synthesized using methane. [Copyright &y& Elsevier]

Abstract: Nano-sized crystals of maghemite iron oxide (γ-Fe2O3) were synthesized onto the surface of NaY-zeolite crystals by immobilizing a polynuclear iron complex [Fe4O2(O2CCH3)7(bpy)2](ClO4) (bpy=2,2′-bipyridine) and subsequent calcination of the material in oxygen. Superparamagnetic γ-Fe2O3 particles with sizes ∼5nm were formed on the surface of the zeolite matrix. The nano-composite, γ-Fe2O3@NaY has been subsequently subjected for thorough characterization with several spectroscopic techniques as well as magnetic and transmission electron microscopic measurements. This confirms the formation of maghemite nanoparticles on a NaY-zeolite surface. γ-Fe2O3@NaY shows a remarkable catalytic efficiency in epoxidation reactions with various olefins using tert-BuOOH as oxidant. Notably, styrene shows a remarkable high conversion (90%) as well as epoxide selectivity (95%) while trans-stilbene is completely converted to its oxide with tert-BuOOH over a γ-Fe2O3@NaY catalyst. [Copyright &y& Elsevier]

Abstract: In this work materials based on iron oxide dispersed over activated carbon were prepared and tested in the H2O2 decomposition and removal of the methylene blue (MB) model from aqueous solution. Two different supports were evaluated: a commercial activated carbon (CAC) and an activated carbon produced by coffee used grounds (ACK). These materials, after iron impregnation (CAC/Fe and ACK/Fe), were characterized using XRD, SEM, N2-sorption, XPS and Mössbauer spectroscopy. The main results suggest the formation of composites with high surface area and iron dispersion containing Fe3+ on the surface of both catalysts. Catalytic tests revealed high capacity for H2O2 decomposition by both composites with more activity for ACK/Fe. MB removal experiments showed intense removal of the model through combined adsorption and oxidation processes. The detection of known MB oxidation intermediates observed by ESI-MS studies confirmed the occurrence of MB oxidation processes and also showed more activity for ACK/Fe. [Copyright &y& Elsevier]

The catalytic efficiency of iron (II, III) oxide to promote Fenton-like reaction was examined by employing Rhodamine B (RhB) as a model compound at neutral pH. Two types of iron (II, III) oxides were used as heterogeneous catalysts and characterized by XRD, Mössbauer spectroscopy, BET surface area, particle size and chemical analyses. The adsorption to the catalyst changed significantly with the pH value and the sorption isotherm was fitted using the Langmuir model for both solids. Both sorption and FTIR results indicated that surface complexation reaction may take place in the system. The variation of oxidation efficiency against H2O2 dosage and amount of exposed surface area per unit volume was evaluated and correlated with the adsorption behavior in the absence of oxidant. The occurrence of optimum amount of H2O2 or of exposed surface area for the effective degradation of RhB could be explained by the scavenging effect of hydroxyl radical by H2O2 or by iron oxide surface. Sorption and decolourization rate of RhB as well as H2O2 decomposition rate were found to be dependent on the surface characteristics of iron oxide. The kinetic oxidation experiments showed that structural FeII content strongly affects the reactivity towards H2O2 decomposition and therefore RhB decolourization. The site density and sorption ability of RhB on surface may also influence the oxidation performance in iron oxide/H2O2 system. The iron (II, III) oxide catalysts exhibited low iron leaching, good structural stability and no loss of performance in second reaction cycle. The sorption on the surface of iron oxide with catalytic oxidation using hydrogen peroxide would be an effective oxidation process for the contaminants. [Copyright &y& Elsevier]

Abstract: The adsorption features of activated carbon and the oxidation properties of iron oxides were combined in a composite to produce new materials for atrazine removal from aqueous medium. Activated carbon/iron oxide composites were prepared at 1/1 and 5/1 mass ratios and characterized with powder X-ray diffractometry (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and nitrogen adsorption measurements. The adsorption and oxidation processes were evaluated in batch experiments, in order to monitor the atrazine removal capacity of these composites. The main iron oxide actually present in the composites was goethite (α-FeOOH). Impregnation with iron oxide reduced the surface area by its deposition in the activated carbon pores. However, a higher iron concentration promoted a higher oxidation rate, indicating that the efficiency of the oxidation reaction is related with the iron content and not with the pre-concentration of the contaminant on the carbon surface through adsorption process. [Copyright &y& Elsevier]

Abstract: The design and control of the surface is extremely important for the development of heterogeneous catalysts because surface properties always play a key role in catalytic performance. Therefore, it is of great interest to investigate the evolution of the surface state during the preparation of a catalyst. Mixed oxides are a particularly important group of catalytic materials. This work studied Fe2O3–MoO3 as a model system, investigating the surface states jointly influenced by the thermal spreading of MoO3 and the solid-state reaction that produces Fe2(MoO4)3 during heat treatment. X-ray photo-electron spectroscopy, scanning electron microscopy and 57Fe Mössbauer analysis were used to characterize the evolution of the surface and the bulk of solids, and the oxidation of methanol to formaldehyde was also used as a probe reaction. It was found that the evolution of the surface layer takes place mainly as follows: (i) a small amount of MoO3 can be dispersed onto the surface of Fe2O3 via grinding; (ii) the thermal spreading of MoO3 and the solid-state reaction start almost simultaneously at around 400°C, leading to the coexistence of MoO3 and Fe2(MoO4)3 species on the surface of Fe2O3 grains; (iii) further thermal spreading and the solid-state reaction yield a shell of Fe2(MoO4)3 encapsulating the remaining Fe2O3 grains, but a small amount of MoO3 remains on the external surface of the resulting Fe2(MoO4)3 shell; (iv) when the MoO3 grains run out, the surface MoO3 species also disappears. [Copyright &y& Elsevier]

Abstract: Iron(II) oxidation in natural waters at circumneutral pH, often regarded as an abiotic process, is frequently biologically mediated at iron-rich redox gradients. West Berry Creek, a small circumneutral tributary that flows through a mixed coniferous forest in Big Basin State Park, California, contains localized iron (hydr)oxide precipitates at points along its course where anoxic groundwater meets oxygenated creek water. These mixing zones establish redox gradients that may be exploited by microbes forming microbial mats that are intimately associated with iron (hydr)oxide precipitates. Water sampling revealed strong correlations between the concentrations of aqueous inorganic species, suggesting a rock-weathering source for most of these solutes. Liquid chromatography–electrospray ionization–mass spectrometry techniques detected significant concentrations of organic exudates, including low molecular mass organic acids and siderophores, indicating that active biogeochemical cycling of iron is occurring in the creek. X-ray diffraction and elemental analysis showed the precipitates to be amorphous, or possibly poorly crystalline, iron-rich minerals. Clone libraries developed from 16S rDNA sequences extracted from microbial mat communities associated with the precipitates revealed the presence of microorganisms related to the neutrophilic iron oxidizing bacteria Gallionella and Sideroxydans. Sequences from these libraries also indicated the presence of significant populations of organisms related to bacteria in the genera Aquaspirillum, Pseudomonas, Sphingomonas, and Nitrospira. These geosymbiotic systems appear to be significant not only for the biogeochemical cycling of iron in the creek, but also for the cycling of organic species, inorganic nutrients, and trace metals. [Copyright &y& Elsevier]

The dechlorination of C6H5Cl and the in situ dry sorption of Cl-compounds produced by C6H5Cl decomposition in an alkaline sorbent of CaO or Na2CO3 incorporated with Fe2O3 were studied. A sample gas containing C6H5Cl at an initial concentration of 500ppm balanced by either N2, O2 (5%)-N2 or H2O (10%)-N2 carrier gas was introduced into a lab-scale quartz tube reactor where CaO or Na2CO3 sorbent was packed with Fe2O3. Subsequently, the effect of Fe2O3 addition to CaO or Na2CO3 on the removal of C6H5Cl, achieved by the decomposition of C6H5Cl as well as the dry sorption of Cl-compounds produced by C6H5Cl decomposition, was investigated. It was found that the decomposition of C6H5Cl in CaO or Na2CO3 sorbent bed incorporated with Fe2O3 occurred in the lower temperatures, compared to the case when only CaO or Na2CO3 sorbent bed was used. Thus, Fe2O3 was found to play a catalytic role in the oxidative decomposition of C6H5Cl. Further, the decomposition of C6H5Cl in a bed containing only Fe2O3 was promoted by the presence of O2 and H2O in the reaction atmosphere. Moreover, a higher amount of Cl was absorbed in the combined CaO/Fe2O3 and Na2CO3/Fe2O3 beds, compared to the absorption of Cl-compounds in only CaO or Na2CO3 sorbent bed. Finally, the comparison of CaO and Na2CO3 sorbents showed that the decomposition of C6H5Cl and the in situ dry sorption of the resultant Cl-compounds in the combined Na2CO3 and Fe2O3 beds were higher than those in the combined CaO and Fe2O3 beds. [Copyright &y& Elsevier]

Abstract: A new immobilized iron oxide (SiG2) was used for the catalytic decomposition of H2O2 and further oxidation of azo dye reactive black B (RBB). The effect of temperature on the catalysis was studied. The decomposition of H2O2 followed pseudo first-order kinetics in the presence of SiG2. The rate constants and activation energy (∼60kJmol−1) of H2O2 decomposition were calculated from the experimental data. The combination of H2O2 and SiG2 were found to be efficient for the degradation of RBB. A two-stage reaction rate law (initiation stage and radical reaction stage) was proposed to simulate the degradation of RBB. The activation energy for RBB degradation at initiation and at radical reaction periods were 20.8 and 83.7kJmol−1, respectively. [Copyright &y& Elsevier]

Abstract: Strongly reducing organic substances (SROS) and iron oxides exist widely in soils and sediments and have been implicated in many soil and sediment processes. In the present work, the sorptive interaction between goethite and SROS derived from anaerobic decomposition of green manures was investigated by differential pulse voltammetry (DPV). Both green manures, Astragalus sinicus (Astragalus) and Vicia varia (Vicia) were chosen to be anaerobically decomposed by the mixed microorganisms isolated from paddy soils for 30d to prepare different SROS. Goethite used in experiments was synthesized in laboratory. The anaerobic incubation solutions from green manures at different incubation time were arranged to react with goethite, in which SROS concentration and Fe(II) species were analyzed. The anaerobic decomposition of Astragalus generally produced SROS more in amount but weaker in reducibility than that of Vicia in the same incubation time. The available SROS from Astragalus that could interact with goethite was 0.69±0.04, 0.84±0.04 and 1.09±0.03cmolkg−1 as incubated for 10, 15 and 30d, respectively, for Vicia, it was 0.12±0.03, 0.46±0.02 and 0.70±0.02cmolkg−1. One of the fates of SROS as they interacted with goethite was oxidation. The amounts of oxidizable SROS from Astragalus decreased over increasing incubation time from 0.51±0.05cmolkg−1 at day 10 to 0.39±0.04cmolkg−1 at day 30, but for Vicia, it increased with the highest reaching to 0.58±0.04cmolkg−1 at day 30. Another fate of these substances was sorption by goethite. The SROS from Astragalus were sorbed more readily than those from Vicia, and closely depended upon the incubation time, whereas for those from Vicia, the corresponding values were remarkably less and apparently unchangeable with incubation time. The extent of goethite dissolution induced by the anaerobic solution from Vicia was greater than that from Astragalus, showing its higher reactivity. [Copyright &y& Elsevier]

Airstreams polluted with H2S at inlet loads ranging from 2.4 to 40.9g H2Sm−3 h−1 were treated in a biotrickling reactor packed with hematite bearing, open pore foam units, at Empty Bed Residence Times (EBRT) ranging from 20 to 60s over a period of 80d, with almost complete removal of the pollutant from the startup of the system. The media had been seeded with sludge from a local water works facility, and removal efficiencies in excess of 80% were consistently observed along the operation of the reactor, with an average of 98%. Based on section performance, being a section one third of the bed length, observed elimination capacities (EC) reached up to 88.7g H2Sm−3 h − 1 and 72.0g H2Sm−3 h−1 at section EBRT of 10 and 7s, respectively. The observed EC values compared much better than data reported on other packed bed reactors using biological iron oxidization to treat H2S airstreams indirectly, and so did it when comparing the EC per unit of specific area in a similar study using polyurethane (PU) foams. Further, and unlike PU packed biofilters, no compaction occurred due to the iron foam rigidity, which translated in much better observed gas phase pressure drop as opposed to other conventional biofilters. Denaturing gel gradient electrophoresis was performed on the biomass collected in the packing after the biofilter service, and it was found that though a multi bacterial colony was seeded in the system via the sludge, the only surviving genus was the iron oxidizing Alicyclobacillus spp. [Copyright &y& Elsevier]

Abstract: Nanoparticle film voltammetry is employed to explore the presence and reactivity of surface-stabilised iron redox centers at the interface of immobilised Fe2O3 nanoparticles of ca. 4nm diameter and aqueous buffer media. Mesoporous films of Fe2O3 nanoparticles on tin-doped indium oxide (ITO) substrates are formed in a layer-by-layer deposition process from aqueous colloidal Fe2O3 and aqueous cyclohexyl-hexacarboxylate followed by thermal (500°C) removal of the organic binder content. Both reversible oxidation and reversible reduction responses for Fe(III) are observed in phosphate and carbonate buffer media in the “underpotential” zone. Higher oxidation states of iron formed anodically (here tentatively assigned to Fe(IV)) are shown to be inert in phosphate buffer media but reactive towards the oxidation of glucose in carbonate buffer media. [Copyright &y& Elsevier]

Abstract: Unsupported “free” nano-γ-Fe2O3 is an active, stable, and reusable catalyst for selective oxidations of alcohols and olefins applying hydrogen peroxide as terminal oxidant. Catalyst activity and selectivity are controlled by tuning the particle size. The formation of a thin carbon-layer on the surface of the nano-iron oxide during the reaction permits for high catalyst stability. All catalysts were characterized by TEM, X-ray photoelectron spectroscopy (XPS), XRD, and EPR. [Copyright &y& Elsevier]