THE CATALYTIC ROLE OF BIRNESSITE IN THE TRANSFORMATION OF IRON

1987 ◽  
Vol 67 (3) ◽  
pp. 533-543 ◽  
Author(s):  
G. S. R. KRISHNAMURTI ◽  
P. M. HUANG
Keyword(s):  
Key Words ◽  
Infrared Absorption ◽  
Molar Ratio ◽  
Acidic Ph ◽  
Chemical Analyses ◽  
X Ray ◽  
Molar Ratios ◽  
Fe Oxides ◽  
Catalytic Role

The influence of birnessite (δ-MnO2) on the precipitation products of iron was studied, in the FeCl2-NH4OH system at different Mn/Fe molar ratios (0, 0.01, 0.1 and 1.0) and in the acidic pH (4.0, 5.0 and 6.0) range, by X-ray, TEM, IR and chemical analyses. The precipitation products formed at pH 5.0 and 6.0 were found to be lepidocrocite (γ-FeOOH) in the absence of birnessite. Birnessite promoted increased precipitation of Fe oxide; the oxidation of Fe(II) by MnO2 was thermodynamically feasible and was confirmed by the presence of Mn(II) in the solution by ESR data. Birnessite also influenced the crystallization processes of hydrolytic products of Fe which range from lepidocrocite through goethite (α-FeOOH), akaganeite (β-FeOOH), to X-ray noncrystalline Fe oxides. The noncrystalline Fe oxides formed at a Mn/Fe molar ratio of 1.0 were characterized by infrared absorption maxima at 1400 and 750 cm−1. Key words: Birnessite, Fe(II) oxidation, ESR, lepidocrocite, akaganeite, noncrystalline oxide

scholarly journals Photocatalytic Reduction of CO2 to Methanol Using a Copper-Zirconia Imidazolate Framework

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 346
Author(s):  
Sonam Goyal ◽  
Maizatul Shima Shaharun ◽  
Ganaga Suriya Jayabal ◽  
Chong Fai Kait ◽  
Bawadi Abdullah ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalyst Support ◽  
Oxidation Potential ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Optimum Parameters ◽  
Reduction Of Co2 ◽  
Enhanced Yield

A set of novel photocatalysts, i.e., copper-zirconia imidazolate (CuZrIm) frameworks, were synthesized using different zirconia molar ratios (i.e., 0.5, 1, and 1.5 mmol). The photoreduction process of CO2 to methanol in a continuous-flow stirred photoreactor at pressure and temperature of 1 atm and 25 °C, respectively, was studied. The physicochemical properties of the synthesized catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The highest methanol activity of 818.59 µmol/L.g was recorded when the CuZrIm1 catalyst with Cu/Zr/Im/NH4OH molar ratio of 2:1:4:2 (mmol/mmol/mmol/M) was employed. The enhanced yield is attributed to the presence of Cu2+ oxidation state and the uniformly dispersed active metals. The response surface methodology (RSM) was used to optimize the reaction parameters. The predicted results agreed well with the experimental ones with the correlation coefficient (R2) of 0.99. The optimization results showed that the highest methanol activity of 1054 µmol/L.g was recorded when the optimum parameters were employed, i.e., stirring rate (540 rpm), intensity of light (275 W/m2) and photocatalyst loading (1.3 g/L). The redox potential value for the CuZrIm1 shows that the reduction potential is −1.70 V and the oxidation potential is +1.28 V for the photoreduction of CO2 to methanol. The current work has established the potential utilization of the imidazolate framework as catalyst support for the photoreduction of CO2 to methanol.

Appearance, corrosion properties, and leach resistance of spruce and pine wood treated with Mea modified micronized copper preservative (MCu)

Holzforschung ◽  
2014 ◽  
Vol 68 (4) ◽  
pp. 477-486 ◽  
Author(s):  
Myung Jae Lee ◽  
Sedric Pankras ◽  
Paul Cooper
Keyword(s):  
Wood Species ◽  
Wood Preservative ◽  
Molar Ratio ◽  
Corrosion Properties ◽  
Pine Wood ◽  
Molar Ratios ◽  
Copper Leaching ◽  
Mold Resistance ◽  
Refractory Wood

Abstract Canadian refractory wood species treated with micronized copper (MCu) wood preservative become mottled and streaky in appearance. To overcome this issue, the MCu system was modified by adding small amounts of monoethanolamine (Mea). The modified systems were evaluated to clarify the role of Mea in terms of leaching, corrosion, and mold resistance of MCu systems. The mottled and streaky surface on treated spruce was prevented at Mea/Cu molar ratios between 0.7 and 1.5. Copper leaching remained modest and was only slightly higher than that of MCu alone up to a Mea/Cu molar ratio of 1.2. However, adding even a small amount of Mea to the MCu formulation increased fastener corrosion compared with MCu. Protonated Mea increased as more Mea was added and was identified as the main corrosion-causing electrolyte in the system.

The Control of the Reactions of Strontium Hexaferrite Formation by the Molar Ratio of Precursors

2007 ◽  
Vol 280-283 ◽  
pp. 471-472
Author(s):  
S.A. Seyyed Ebrahimi
Keyword(s):  
Critical Parameters ◽  
Molar Ratio ◽  
Strontium Hexaferrite ◽  
Strontium Oxide ◽  
Molar Ratios ◽  
Temperature Method ◽  
Wide Range ◽  
Method Of Production ◽  
Thermal Analysis Techniques

Strontium hexaferrite is one of the very important categories of magnetic materials with a wide range applications. One of the very critical parameters in the high temperature method of production of this material is molar ratio of iron oxide to strontium oxide. Although there could be found some reports on the effect of this parameter on the physical properties of the material in the literature but there are very few investigations about the role of this factor on the reactions occurred in the process. In this work the effect of different molar ratios of precursors on the reactions carried out for processing of strontium hexaferrite have been investigated by using thermal analysis techniques such as DTA/TG. Furthermore, the microstructure and the powder and bulk magnetic properties of the products have been studied by SEM, VSM and permeameter.

Synthesis of Fe2O3/C Nanocomposite Using Microwave Assisted Calcination Method

2014 ◽  
Vol 896 ◽  
pp. 100-103 ◽  
Author(s):  
Anggi Puspita Swardhani ◽  
Ferry Iskandar ◽  
Abdullah Mikrajuddin ◽  
Khairurrijal
Keyword(s):  
Crystallite Size ◽  
Average Particle Size ◽  
Molar Ratio ◽  
Average Particle ◽  
X Ray ◽  
Molar Ratios ◽  
Microwave Assisted ◽  
Chloride Hexahydrate ◽  
Calcination Method ◽  
Scherrer Method

Fe2O3/C nanocomposites were successfully synthesized using microwave assisted calcination method. Ferric (III) chloride hexahydrate (FeCl36H2O), sodium hydroxide (NaOH), and dextrose monohydrate (C6H12O6H2O) were used as precursors. A microwave oven of 2.445 GHz with a power of 600 W for 20 minutes was employed during the syntheses. Calcination was performed in a simple furnace at 350 °C for 30 min. The molar ratio of C:Fe is the only process parameter. From Scanning Electron Microscope images, the average particle size were 199 nm and 74 nm for the samples with molar ratio of C:Fe of 1:2 and 1:1, respectively. X-ray diffractometer spectra showed that the obtained samples have γ-Fe2O3 (maghemite) crystal structure. Using the Scherrer method, the crystallite size were 61.7, 58.8, 52.5, and 48.8 nm for the samples with the molar ratios of C:Fe of 1:3, 1:2, 1:1, and 2:1, respectively. It means that the crystallite size of the nanocomposite decreases with the increase of the molar ratio of carbon to iron (C:Fe). The Brunauer-Emmett-Teller characterization showed that the surface area as high as 255.6 m2/g is achieved by of the Fe2O3/C nanocomposite with the molar ratio of C:Fe of 1:1.

scholarly journals Role of Iron in Hydrogen Sulphide Removal from Hot Gas

1987 ◽  
Vol 4 (4) ◽  
pp. 230-240 ◽  
Author(s):  
E. Furimsky ◽  
A. Palmer ◽  
M.E. Brett ◽  
R. Provencher ◽  
M. Yumura
Keyword(s):  
Mössbauer Spectroscopy ◽  
Hydrogen Sulphide ◽  
Red Mud ◽  
Mossbauer Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Component Distribution ◽  
Hot Gas ◽  
Fe Oxides

Yields of SO2 formed during H2S removal from N2 + H2S mixture at 800°C in the presence of Fe2O3, Mn-nodule and red mud have been determined. The largest yields were observed for Fe2O3 followed by Mn-nodule, whereas no SO2 was detected in the presence of red mud. A mechanism for H2S reaction with Fe oxides has been proposed involving the use of the component distribution in the clean gas as well as the Fe sulphides formed during adsorption. X-ray diffraction and Mossbauer spectroscopy have been used to determine the forms of Fe in the solids at the end of adsorption. FeS was the main sulphide which was always accompanied by FeS2.

Cathode Material Li [Li0.2 Mn0.44Ni0.18Co0.18]O2 Synthesized by Molten Salt Method

2013 ◽  
Vol 690-693 ◽  
pp. 981-984
Author(s):  
Guang Xin Fan ◽  
Hui Lian Li ◽  
Shu Pu Dai ◽  
Chuan Xiang Zhang ◽  
Xue Mao Guan ◽  
...  
Keyword(s):  
Molten Salt ◽  
Specific Area ◽  
Constant Current ◽  
Molar Ratio ◽  
Molten Salt Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Structures And Properties ◽  
Constant Current Charge

In this paper, LiOH·H2O and Li2CO3, which were widely used in industry and (Mn0.533Co0.233Ni0.233) (OH)2prepared by ourselves selected as starting materials, series materials of lithium-rich layered material Li [Li0.2Mn0.44Ni0.18Co0.18]O2were obtained by a molten salt method. Their structures and properties of the materials were investigated by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and constant current charge/discharge methods. The effects of different LiOH and Li2CO3molar ratios on the Li [Li0.2Mn0.44Ni0.18Co0.18]O2structures and properties were characterized. The results of the experiments indicate that The structures of the material such as crystal structure, the specific area, particle size distribution, tap densities were controlled by adjusting the proportion of the two lithium sources. Forthermore , when the molar ratio of LiOH and Li2CO3was 3:7, the maximum discharge capacity (214.77 mAhg-1) of the cathode was obtained.

Nickel and cobalt phosphides as effective catalysts for oxygen removal of dibenzofuran: role of contact time, hydrogen pressure and hydrogen/feed molar ratio

2015 ◽  
Vol 5 (6) ◽  
pp. 3403-3415 ◽  
Author(s):  
A. Infantes-Molina ◽  
E. Gralberg ◽  
J. A. Cecilia ◽  
Elisabetta Finocchio ◽  
E. Rodríguez-Castellón
Keyword(s):  
Catalytic Activity ◽  
Contact Time ◽  
Hydrogen Pressure ◽  
Oxygen Removal ◽  
Molar Ratio ◽  
Metal Loading ◽  
Molar Ratios ◽  
Feed Molar Ratio

The catalytic activity of nickel and cobalt phosphides, with a metal loading of 5 wt.%, supported on silica was investigated in the hydrodeoxygenation reaction (HDO) of dibenzofuran (DBF) as a model oxygenated compound at different contact times, H2 pressures and H2/DBF molar ratios.

Geminal bis(hypersilyl) compounds — the synthesis and structure of bis[tris(trimethylsilyl)silyl]silanes

2000 ◽  
Vol 78 (11) ◽  
pp. 1399-1404
Author(s):  
Thoralf Gross ◽  
Helmut Reinke ◽  
Hartmut Oehme
Keyword(s):  
Crystal Structure ◽  
Key Words ◽  
Trifluoromethanesulfonic Acid ◽  
Molar Ratio ◽  
Coupling Reactions ◽  
Subsequent Reaction ◽  
X Ray ◽  
A Value ◽  
Spatial Demand

Protodesilylation of diphenylsilane with trifluoromethanesulfonic acid and subsequent reaction of the obtained bis(trifluoromethanesulfonyloxy)silane with tris(trimethylsilyl)silyllithium (1) (molar ratio 1:2) afforded bis[tris(trimethylsilyl)silyl]silane (8). Methyl-bis[tris(trimethylsilyl)silyl]silane (3) and phenyl-bis[tris(trimethylsilyl)silyl]silane (10) were obtained by coupling reactions of 1 with MeHSiCl2 or PhHSiCl2, respectively, (2:1). By treatment with HCBr3, the H-silanes 3, 8, and10 were converted into the bromosilanes [(Me3Si)3Si]2SiR1R2 (9: R1 = R2 = Br; 11: R1 = Me, R2 = Br; 12: R1 = Ph, R2 = Br). X-ray crystal structure analyses, performed for 3, 10 and 12, confirmed the expected distortions of the molecular skeletons of the compounds. Thus, e.g., in 10, the spatial demand of the two extended hemispherical hypersilyl groups forces a widening of the Si-Si-Si angle at the central Si atom to a value of 128.3°.Key words: silanes, sterically congested, bis(hypersilyl)silanes, hypersilylsilanes, bis(hypersilyl)germanes, tris(trimethylsilyl)silylsilanes.

scholarly journals Structural, Surface Morphology and Optical Properties of ZnS Films by Chemical Bath Deposition at Various Zn/S Molar Ratios

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Fei-Peng Yu ◽  
Sin-Liang Ou ◽  
Pin-Chuan Yao ◽  
Bing-Rui Wu ◽  
Dong-Sing Wuu
Keyword(s):  
Chemical Bath Deposition ◽  
Photoelectron Spectroscopy ◽  
Visible Region ◽  
Film Surface ◽  
Optical Transmittance ◽  
Molar Ratio ◽  
Infrared Spectrometry ◽  
X Ray ◽  
Molar Ratios ◽  
Zns Films

In this study, ZnS thin films were prepared on glass substrates by chemical bath deposition at various Zn/S molar ratios from 1/50 to 1/150. The effects of Zn/S molar ratio in precursor on the characteristics of ZnS films were demonstrated by X-ray diffraction, scanning electron microscopy, optical transmittance, X-ray photoelectron spectroscopy, and Fourier transform infrared spectrometry. It was found that more voids were formed in the ZnS film prepared using the precursor with Zn/S molar ratio of 1/50, and the other ZnS films showed the denser structure as the molar ratio was decreased from 1/75 to 1/150. From the analyses of chemical bonding states, the ZnS phase was indeed formed in these films. Moreover, the ZnO and Zn(OH)2also appeared due to the water absorption on film surface during deposition. This would be helpful to the junction in cell device. With changing the Zn/S molar ratio from 1/75 to 1/150, the ZnS films demonstrate high transmittance of 75–88% in the visible region, indicating the films are potentially useful in photovoltaic applications.

scholarly journals Liquid petroleum gas sensing performance enhanced by CuO modification of nanocrystalline ZnO-TiO2

2016 ◽  
Vol 34 (3) ◽  
pp. 571-581
Author(s):  
R.B. Pedhekar ◽  
F.C. Raghuwanshi ◽  
V.D. Kapse
Keyword(s):  
Thick Film ◽  
Gas Sensing ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Transmission Electron ◽  
Liquid Petroleum Gas ◽  
Synthesized Materials ◽  
Sensing Characteristics

AbstractNanocrystalline ZnO-TiO2 (with molar ratios 9:1, 7:3, 1:1, 3:7 and 1:9) were successfully synthesized by hydrothermal method. Synthesized materials were examined with the help of X-ray diffraction and transmission electron microscope. Liquid petroleum gas sensing characteristics of the ZnO-TiO2 films were investigated at different operating temperatures. The ZnO-TiO2 thick film (with 1:1 molar ratio) exhibited good response toward liquid petroleum gas as compared to other investigated compositions. Further, liquid petroleum gas sensing characteristics of CuO modified ZnO-TiO2 thick films were investigated. 0.2 M CuO modified ZnO-TiO2 thick film exhibited excellent liquid petroleum gas sensing characteristics such as higher response (~ 1637.49 at 185 °C) with quick response time (~30 s), low recovery time (~70 s), excellent repeatability and stability at low operating temperature.

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