Sorption of microamounts of gallium(III) on Fe(OH)3 and Fe2O3 precipitates

Summary The sorption of microamounts of gallium(III) on Fe(OH)₃ and Fe₂O₃ precipitates was studied by using⁶⁷Ga as radioactive indicator. The dependence of sorption of microamounts of gallium(III) on pH, sorbent concentration, and duration of the contact between gallium-(III) and Fe(OH)₃ precipitate, was established. In the presence of sodium citrate the sorption of microamounts of gallium (III) on Fe₂O₃ markedly decreased. Iron(III) hydroxide and Fe₂O₃ precipitates are suitable collectors for the preconcentration of gallium (III) traces in solution.

---

Zusammenfassung Die Adsorption von Mikromengen Ga(III) an Niederschlägen von Fe(OH)₃ und Fe₂O₃ wurde mit Hilfe von⁶⁷Ga als radioaktivem Indikator untersucht. Die Abhängigkeit der Adsorption vom pH, von der Konzentration des Sorptionsmittels und von der Dauer des Kontakts zwischen Ga(III) und Fe(0H)₃ wurde festgestellt. In Gegenwart von Na-Citrat wird die Sorption an Fe₂O₃ merklich geringer. Eisen (III)hydroxid- und Fe₂O₃-Niederschläge eignen sich als Kollektoren zur Anreicherung von Ga(III)-Spuren in einer Lösung.

     

Thermal decomposition of hydronium jarosite (H3O)Fe3(SO4)2(OH)6

Thermogravimetry combined with mass spectrometry has been used to study the thermal decomposition of a synthetic hydronium jarosite. Five mass loss steps are observed at 262, 294, 385, 557 and 619°C. The mass loss step at 557°C is sharp and marks a sharp loss of sulphate as SO₃ from the hydronium jarosite. Mass spectrometry through evolved gases confirms the first three mass loss steps to dehydroxylation, the fourth to a mass loss of the hydrated proton and a sulphate and the final step to the loss of the remaining sulphate. Changes in the molecular structure of the hydronium jarosite were followed by infrared emission spectroscopy. This technique allows the infrared spectrum at the elevated temperatures to be obtained. Infrared emission spectroscopy confirms the dehydroxylation has taken place by 400 and the sulphate loss by 650°C. Jarosites are a group of minerals formed in evaporite deposits and form a component of the efflorescence. The minerals can function as cation and heavy metal collectors. Hydronium jarosite has the potential to act as a cation collector by the replacement of the proton with a heavy metal cation.     

Synthesis,characterization and thermal behaviour of Fe4(OH)11NO3·2H2O

A new iron basic salt, Fe₄(OH)₁₁NO₃·2H₂O, has been prepared by partially hydrolyzing a solution of Fe(NO₃)₃·9H₂O with urea. The X-ray powder diffraction pattern has been indexed within a monoclinic cella=9.99(3) ?,b=9.48(2) ?,c=3.074(3) ? andβ=90.57(1)°. Thermal decomposition reactions in still air and nitrogen flow have been studied by DTA and TG analysis, and the intermediate and final products have been characterized by X-ray diffraction and IR spectroscopy. When this material is thermally decomposed in an X-ray high temperature diffraction chamber, pure iron is formed at 900 °C together with Fe(III) and Fe(II) oxides.

---

Zusammenfassung Mittels Hydrolyse einer L?sung von Fe(NO)₃)₃·9H₂O mit Karbamid wurde das neue basische Eisensalz Fe₄(OH)₁₁NO₃·2H₂O dargestellt. Aus einem R?ntgenpulververfahren resultierena=9,55(3) ?,b=9,48(2) ?,c=3,074(3) ? undβ=90,57(1)° für eine monozyklische Zelle. Mittels DTA- und TG-Untersuchungen wurden die thermischen Zersetzungsreaktionen an Luft und im Stickstoffflu? untersucht und die Zwischen- und Endprodukte mit r?ntgendiffraktionsverfahren und IR-Spectroskopie charakterisiert. Bei einer thermischen Zersetzung dieses Stoffes in einer Hochtemperatur-r?ntgendiffraktionskammer wird bei 900 °C elementares Eisen zusammen mit Fe(II)- und Fe(III)-oxiden gebildet.

---

Резюме Частичным гидролизо м раствора соли Fe(NO₃)₃ · 9H₂O с мочевиной получен а новая основная соль Fe₄(OH)₁₁NO₃ · 2Н₂О, для которой методо м порошкового рентген оструктурного анализа была установ лена моноклинная стр уктура с параметрами ячейкиа=9,55(3) А,b=9,48(2) ?,c=3,074(3) ? иβ=90,57(1)°. Термиче ское разложение соли изучено методом ДТА и ТГ в динамическо й атмосфере воздуха и азота, а образующиеся промеж уточные и конечные продукты ре акции были охарактер изованы рентгенофазовым ана лизом и ИК спектроскопией. ˉПри термическом разложе нии соли в высокотемпературно й рентгено-диффракци онной камере при 900° образует ся чистое железо вмес те с оксидами двух- и трехвалентного желе за.

---

---

The authors are greateful to Dr. R. M. Rojas for his helpful suggestions.     

Structure, electrochemistry, and magnetism of the iron(III)-substituted Keggin dimer, [Fe6(OH)3(A-alpha-GeW9O34(OH)3)2]11-

The iron(III)-substituted tungstogermanate [Fe6(OH)3(A-alpha-GeWO34(OH)3)2]11- (1) has been synthesized and characterized by IR, elemental analysis, SQUID magnetometry, electron paramagnetic resonance (EPR), and electrochemistry. Single-crystal X-ray analysis was carried out on Cs4Na7[Fe6(OH)3(A-alpha-GeW9O34(OH)3)2] x 30H2O, which crystallizes in the monoclinic system, space group C2/m, with a = 36.981(4) A, b = 16.5759(15) A, c = 16.0678(15) A, beta = 95.311(3) degrees, and Z = 4. Polyanion 1 consists of two (A-alpha-GeW9O34) Keggin moieties linked via six Fe3+ ions, leading to a double-sandwich structure. The equivalent iron centers represent a trigonal prismatic Fe6 fragment, resulting in virtual D3h symmetry for 1. Electrochemistry studies revealed that 1 is stable in solution from pH 3 to at least pH 7. In pH = 3 media the reduction of the six Fe3+ centers was featured by a single voltammetric wave for most supporting electrolytes used. In that case, whatever the scan rate from 1000 mV x s(-1) down to 2 mV x s(-1), no splitting of the single Fe-wave of 1 was observed. The acetate medium induced a partial splitting of the wave, and this separation is enhanced with increasing pH. Remarkable efficiency of 1 in the electrocatalytic reduction of nitrite, nitric oxide, and nitrate is demonstrated. Magnetic susceptibility (chi) measurements indicate a diamagnetic (S(T) = 0) ground state, with an average J = -12 cm(-1) and g = 2.00. EPR studies confirm that the ground state is indeed diamagnetic, since the EPR signal intensity steadily decreases without any line broadening as the temperature is lowered and becomes unobservable below about 50 K. The signal is a single broad peak at all frequencies (90-370 GHz), ascribed to the thermally accessible excited states. Its g(iso) is 1.992 51, as expected for a high-spin Fe3+-containing species, and supports the chi data analysis.     

Redox Equilibria in the System Fe(OH)3(H2SO4)-Na2SO3-H2O Involving Precipitation of Iron(II) Sulfite as a Fe2O3 Precursor

Experimental data on the equilibria Fe²⁺/Fe³⁺ and SO₃ ²⁻/SO₄ ²⁻ in the system Fe(OH)₃(H₂SO₄)-Na₂SO₃-H₂O are presented. The quantitative relations between the reduction of Fe(III) and the precipitation of FeSO₃·2.5H₂O as a Fe₂O₃ precursor have considered graphically.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 1, 2005, pp. 41–44.Original Russian Text Copyright © 2005 by Vasekha, Motov.     

OH stretch IR spectra of (H2O)3 and benzene-(H2O)3

The OH stretch IR spectrum of (H₂O)₃ is significantly altered upon complexation of the cluster with a benzene molecule. Theoretical calculations show that the differences in the OH stretch spectra of (H₂O)₃ and benzene-(H₂O)₃ are primarily due to mode localization induced by the benzene molecule. Received: 27 January 1997 / Accepted: 28 January 1997     

Crystal Structure of [CH_3CH(OH)COO]_2Fe(H_2O)_2·H_2O

<正> The title compound C6H16O9Fe, Mr = 288. 13, was synthesized and crystallized in monoclinic space group P21/c, a = 9. 409(4), b = 5. 812(4), c= 22. 122(7)(?) , β=90. 80(3)°. V = 1209. 6(?)3, Z = 4, Dc=1. 572g/cm3, F(000) = 592, μ = 12. 73cm-1, R = 0. 063, Rw= 0. 068 for 1191 observed reflections. The iron atom is surrounded by O(1 - 6) in a distorted octahedron.     

Crystal structure and heat capacity of the mixed-valence trinuclear iron monoiodoacetate complex, [Fe(III)2Fe(II)O(O2CCH2I)6(H2O)3][Fe(III)3O(O2CCH2I)6(H2O)3]I

The crystal structure of a trinuclear iron monoiodoacetate complex was determined. Although it has been incorrectly characterized as [Fe₃O(O₂CCH₂I)₆(H₂O)₃], the correct chemical formula turned out to be [Fe(III)₂Fe(II)O(O₂CCH₂I)₆(H₂O)₃]-[Fe(III)₃O(O₂CCH₂I)₆(H₂O)₃]I (1). The two kinds of Fe₃O molecules (Fe(III)₂Fe(II)O and Fe(III)₃O) are crystallographically indistinguishable. All the Fe atoms are crystallographically equivalent because of a crystallographic threefold symmetry. Heat capacities of 1 seem to exhibit no thermal anomaly in the temperature range 5.5–309 K, although the valence detrapping phenomenon has been observed in this temperature range. This fact indicates that the valence-detrapping phenomenon in 1 occurs without any phase transition, leading 1 to a glassy state, probably because the crystal of 1 is just like a solid solution of distorted mixed-valence Fe(III)₂Fe(II)O molecules and permanently undistorted Fe(III)₃O molecules which may act as an inhibitor for a cooperative valence-trapping.     

Polymer imprinting with iron-oxo-hydroxo clusters: [Fe6O2(OH)2(O2CC(Cl)=CH2)12(H2O)2], [Fe6O2(OH)2(O2C-Ph-(CH)=CH2)12(H2O)2] and [{Fe(O2CC(Cl)=CH2)(OMe)2}10

We report the syntheses of imprinted polymers using iron-oxo-hydroxo clusters as templates. Three new iron clusters, [Fe(6)O(2)(OH)(2)(O(2)CC(Cl)=CH(2))(12)(H(2)O)(2)] (1), [{Fe(O(2)CC(Cl)=CH(2))(OMe)(2)}(10)] (2) and [Fe(6)O(2)(OH)(2)(O(2)C-Ph-(CH)=CH(2))(12)(H(2)O)(2)] (3) have been prepared from commercially-available carboxylic acids. Cluster-imprinted-polymers (CIPs) of 1, 2 and 3 were prepared with ethylene glycol dimethacrylate monomer, and of 1 with methyl methacrylate monomer. The imprinted sites within the CIPs were examined using EXAFS and diffuse reflectance UV/vis spectroscopy, demonstrating that the clusters 1, 2 and 3 were incorporated intact within the polymers. Extraction of the clusters from the CIPs imprinted with 1 and 3 gave new polymers that showed evidence of an imprinting effect.     

三核铁苯甲酸配合物[Fe3O(OBz)6(CH3OH)3](NO3)(CH3OH)2的电子光谱及其理论分析

测定了三核苯甲酸铁配合物[Fe₃O(OBz)₆(CH₃OH)₃](NO₃)(CH₃OH)₂(OBz^-=苯甲酸根)的电子光谱,应用配体场理论和T-S图求得配体场参数10Dq=12457cm^-1.用CNDO/2方法对其简化模型进行了计算。     

Synthesis and structure of asymmetric zirconium-substituted silicotungstates, [Zr6O2(OH)4(H2O)3(beta-SiW10O37)3]14- and [Zr4O2(OH)2(H2O)4(beta-SiW10O37)2]10-

The reaction of ZrCl4 with [gamma-SiW10O36]8- in a potassium acetate buffer results in two different products depending on the reactant ratios. The trimeric species [Zr6O2(OH)4(H2O)3(beta-SiW10O37)3]14- (1) consists of three beta23-SiW10O37 units linked by an unprecedented Zr6O2(OH)4(H2O)3 cluster with C1 point group symmetry. The dimeric species [Zr4O2(OH)2(H2O)4(beta-SiW10O37)2]10- (2) consists of beta22- and beta12-SiW10O37 units sandwiching a Zr4O2(OH)2(H2O)4 cluster, which also has C1 symmetry. Polyanion 1 contains more zirconium centers than any other polyoxometalate known to date.     

Synthesis of Fe3O4, Fe2O3, Ag/Fe3O4 and Ag/Fe2O3 nanoparticles and their electrocatalytic properties

Two important iron oxides:Fe3O4 and Fe2O3,as well as Fe3O4 and Fe2O3 nanoparticles mingling with Ag were successfully synthesized via a hydrothermal procedure.The samples were confirmed and characterized by X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The morphology of the samples was observed by transmission electron microscopy(TEM).The results indicated Fe3O4,Fe2O3,Ag/Fe3O4 and Ag/Fe2O3 samples all were nanoparticles with smaller sizes.The samples were modified on a glassy carbon electrode and their elctrocatalytic properties for p-nitrophenol in a basic solution were investigated.The results revealed all the samples showed enhanced catalytic performances by comparison with a bare glassy carbon electrode.Furthermore,p-nitrophenol could be reduced at a lower peak potential or a higher peak current on a glassy carbon electrode modified with Ag/Fe3O4 or Ag/Fe2O3 composite nanoparticles.     

The structure and magnetic properties of μ3-oxotriiron(III) complex [Fe3O(OBz)6(CH3OH)3](NO3)(CH3OH)2

A new μ₃-O triiron(III) complex [Fe₃O(OBz)₆(CH₃OH)₃](NO₃)(CH₃OH)₂ (HOBZ = benzoic acid) has been synthesized, its structure has been determined and variable temperature magnetic susceptility has also been measured. In the molecule, three iron atoms formed an equilateral triangle with μ₃-O in center. The fitting to the magnetic susceptibility showed that an intramolecular antiferromagnetic exchange interaction occurred between iron atoms with J=-25.51 cm^?1, and a weaker intermolecular autiferromagnetic exchange interaction occurred with zJ' = ?2.30 cm^?1.     

Ferromagnetische Phase in Produkten des Kochprozesses von Cd(OH)2/Fe(OH)3

In the system CdO·xFe₂O₃ formed from co-precipitated and boiled hydroxides of Cadmium(II) and Iron(III) the following can be identified by X-ray study: atx0.8-besides the Cd(OH)₂ phase--Fe₂O₃, at 1.5x0.8 fine crystalline -Fe₂O₃ and traces of -Fe₂O₃, at 4>x>1.5 both modifications, i.e. -Fe₂O₃ and -Fe₂O₃, and atx>4 only -Fe₂O₃.The course of specific magnetisation as a function of composition confirms the X-ray findings.

---

---

Mit 3 Abbildungen     

Raman spectroscopic study of the uranyl minerals vanmeersscheite U(OH)4[(UO2)3(PO4)2(OH)2].4H2O and arsenouranylite Ca(UO2)[(UO2)3(AsO4)2(OH)2].(OH)2.6H2O

Raman and infrared spectra of secondary uranyl phosphate vanmeersscheite and Raman spectrum of secondary uranyl arsenate arsenuranylite were recorded and interpreted, and the spectra related to the structure of the minerals. Observed bands were attributed to the stretching and bending vibrations of uranyl, phosphate and/or arsenate units and OH (H(2)O and OH(-)) units. Phosphuranylite sheet topology is characteristic for both minerals. U-O bond lengths in uranyl were calculated from the spectra and compared with those inferred for vanmeersscheite from the X-ray single crystal structure analysis. O-H...O hydrogen bonds in both minerals were also inferred using the Libowitzky empirical relation.     

Synthesis, characterization, and electrochemical application of Ca(OH)2-, Co(OH)2-, and Y(OH)3-Coated Ni(OH)2 tubes

We report on the synthesis, characterization, and electrochemical application of Ca(OH)2-, Co(OH)2-, and Y(OH)3-coated Ni(OH)2 tubes with mesoscale dimensions. These composite tubes were prepared via a two-step chemical precipitation within an anodic alumina membrane under ambient conditions. The morphology and structure of the as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) equipped with energy dispersive spectroscopy (EDS). The results showed that the size of the tubes was of mesoscale dimension and the proportion of the tube morphology was about 95%. The as-prepared composite tubes were further investigated as the positive-electrode materials of rechargeable alkaline batteries. Electrochemical measurements revealed that the Ni(OH)2 tubes coated with Ca(OH)2, Co(OH)2, and Y(OH)3 exhibited superior electrode properties including high discharge capacity, excellent high-temperature and high-rate discharge ability, and good cycling reversibility. The mechanism analysis suggests that both the coated layers and the unique hollow-tube structures play an indispensable role in optimizing the electrochemical performance of nickel hydroxide electrodes.     

Untersuchungen an Kobalt-Zink-Hydroxid,Co3Zn2(OH)10, 2H2O

A new cobalt-zinc-hydroxide with the composition Co₃Zn₂(OH)₁₀ · 2 H₂O is described. The X-ray powder diffraction pattern can be indexed with a monoclinic cell, a = 5.49 Å, b = 6.22 Å, c = 15.45 Å, β = 100.7º. A possible structure of this new compound, with cobalt ions in octahedral and zinc ions in tetrahedral coordination, is proposed.