Aqueous Solution Of Ferric Chloride Research Articles

Calorimetric investigation of complex formation in the aqueous Fe (III)–citrate system

We have made calorimetric measurements of thermal effects associated with adding NaOH(aq) or HCl(aq) to aqueous solutions (pH = 1.623) of ferric chloride + sodium citrate. Combination of these measured heats with concentrations of various species calculated from stoichiometric compositions and previously known K and ΔH values leads to ΔH values for four aqueous Fe(III)–citrate complexes. Further combination of ΔG0 values from equilibrium constants with our ΔH values leads to ΔS0 values, which are discussed in relation to conventional ideas about relationships between entropy and solute–water interactions.

Properties of ion exchange membranes anisotropically combined with conducting polymers. III. Formation of lithium cell composed of lithium and anion exchange membranes with polypyrrole layer

Composite membranes with a polypyrrole layer were produced by contacting one side of anion exchange membranes in which pyrrole had been adsorbed, with an aqueous ferric chloride solution. Various kinds of anion exchange membranes were used and their morphology was examined. After the composite membrane had been swollen with propylene carbonate, a lithium cell was assembled with the composite membrane and lithium foil (emf: 3.2–3.5 V). Discharge behavior of the cell was examined in connection with membrane species. The capacity of the cell was dependent on the fixed ion concentration of the anion exchange membrane but was independent of the amount of polypyrrole on the membrane surface. It is thought that the properties of the polypyrrole formed on the membrane surface changed according to the fixed ion concentration of the membrane. The discharge capacity of the cell exceeded the amount of Cl - that was doped on the polypyrrole. The cell was also evaluated as a rechargeable cell.

Magnetic properties of fine Fe-Co-B particles prepared by chemical reduction

The effect of chemical composition and particle size on the magnetic properties of Fe-Co-B fine particles has been studied. The powders were produced by chemical reduction of aqueous solutions of ferric chloride and cobalt chloride with sodium borohydride. The structure of the initially reduced powders varied from amorphous to crystalline bcc depending on the boron concentration. Chemical composition analysis showed a boron content in the range 5–30 at. %. The particle size was found to be 25 nm. The magnetization and coercivity of as-made powders were relatively low. After annealing, the maximum values of magnetization and coercivity obtained were about 160 emu/g and 1940 Oe, respectively. The temperature coefficient of coercivity varied from negative to positive with sample composition and packing fraction.

A model for the rate of catalytic oxidation of methanol in a fixed bed reactor

AbstractOxidation of methanol to formaldehyde, using a mixture of ferric and molybdenum oxides as catalyst, has been studied in a fixed bed integral reactor, 150 mm long, 25 mm o.d. and 10 mm i.d. The catalyst was prepared by reaction between aqueous solutions of ammonium heptamolybdate and ferric chloride. It has been shown that, under experimental conditions similar to those employed in industry, neither external nor internal diffusion had been effective in the process and isothermal conditions prevailed in both gas and solid phases. A two‐step mechanism has been put forward for the oxidation of methanol. According to such a mechanism, methanol is first oxidized to formaldehyde, accepting an oxygen molecule from the catalyst and changing the latter into a reduced form. In the second step, the reduced catalyst is transformed into the original form on obtaining an oxygen molecule from the gas phase. Based on this scheme, a rate model has been derived and verified by experimental results.

Corrosion and stress corrosion cracking of amorphous FeNiMoxB alloys in several neutral and acidic media

AbstractCorrosion and stress corrosion cracking behaviour of a series of amorphous iron alloys FeNiMoxB (x = 0, 2, 4, 8.5) has been investigated in several neutral and acidic media.In particular in aqueous solutions of ferric chloride, potassium tetrathionate and sulphuric acid containing chlorides stress corrosion cracking (SCC) has been studied by means of constant strain tests and corrosion rates have been evaluated by means of weight loss measurements. In several cases polarization curves have been recorded in order to clarify the electrochemical behaviour of the amorphous alloys. SEM observations of the fracture surfaces have been performed.It has been observed that the glassy alloys under investigation are susceptible to SCC at free corrosion potential in all the environments. SCC has been observed on specimens cathodically and anodically polarized in sulphuric acid containing chlorides. Hydrogen embrittlement can reasonably be considered responsible of the SCC phenomenon, except in sulphuric acid solution on specimens anodically polarized and in iron chloride solution.A deleterious effect of molybdenum has been noted on the corrosion rates of unstressed specimens and on the time to failures of stressed samples.

Effect of magnetic field on the rate of steel corrosion in aqueous solutions

The effect of magnetic field on the diffusion controlled corrosion of steel in aqueous solution of ferric chloride was studied using the loss in weight method. Variables studied were ferric chloride concentration and magnetic field intensity. The rate of corrosion was found to decrease at low magnetic field intensities below the value measured in the absence of the magnetic field. With increasing magnetic field intensity the rate of corrosion increases again and may exceed the value measured in the absence of magnetic fields. Results were explained on the basis of the presence of two opposing flows.

Improved Spray Reagent for Thin Layer Chromatographic Method for Detecting Uric Acid: Collaborative Study

A collaborative study was conducted to validate the substitution of an improved single spray in the official AOAC thin layer chromatographic method for identifying uric acid (UA) from bird and insect excreta. The proposed reagent, which is a dilute aqueous solution of ferric chloride and potassium ferricyanide, requires neither a heating step nor a pH indicator. Its preparation time, specificity, and sensitivity to low levels (5-50 ng) of UA were compared with those of the official sprays. The improved spray took 1/5 as long to prepare as the official sprays. Neither the proposed spray nor the official sprays gave false positive reactions with compounds similar to UA. For bird and insect excreta samples, at the 95% confidence limits, the false negative rate was between 0 and 9.7% for the proposed spray and between 0.7 and 18.7% for the official sprays. Sensitivity results showed that the proportion positive for the proposed spray was significantly higher (P less than 0.05) than for the official sprays at the 15 ng UA level. The proposed changes have been adopted official first action.

The Stress Corrosion Behavior of Glassy Fe-40Ni-20B Alloy in Aqueous Acidic Media

Abstract The stress corrosion behavior of commercially available glassy Fe-40 At% Ni-20 At% B alloy was investigated. Constant strain testing was carried out in aqueous solutions of ferric chloride, polythionic acid, and hydrochloric acid. Weight loss and selective dissolution experiments at the free corrosion potential and linear polarization studies were also performed in these media. The potential dependence of crack morphology showed a progression from hydrogen embrittlement at cathodic potentials through general dissolution to stress corrosion cracking and crevice corrosion at anodic potentials. Selective leaching of nickel from pits and cracks was observed in chloride media. Crack morphology depended somewhat on surface topography.

Dissolution kinetics of krypton-irradiated lithium fluoride

Dissolution characteristics of Kr-irradiated lithium-fluoride in aqueous solutions of ferric chloride are reported. Nucleation of pits was observed to depend on the dose of irradiation. A dose of 10 15 and 10 16 ions/cm 2 caused a uniform dissolution rate of the surface without any pit formation, but a dose of 10 13 and 10 14 ions/cm 2 was observed to cause pitting even in the presence of radiation damage. In the former case, uniform dissolution is explained by the relative increase in the density of defect clusters formed by the coalescence of individual Frenkel defects. At the threshold dose for uniform dissolution, distance between two nucleation sites of dissolution was theoretically analysed to be 80 Å.

Kinetics of dissolution of zinc sulphide in aqueous ferric chloride solution

Studies on the kinetics of dissolution of chemical grade zinc sulphide powder in aqueous ferric chloride solutions of concentration range of 0.2 to 0.8 mol dm −3 at temperatures ranging from 30 to 70°C are reported. The dissolution rate follows a parabolic equation which fits well with the model of Crank-Ginstling and Brounschtein. The activation energy of the dissolution process has been found to be 90.0 ± 12.5 kJ mol −1. It is suggested that a film of elemental sulphur is formed on the zinc sulphide surface during its dissolution with ferric chloride. Inward diffusion of the ferric ion through this layer has been suggested to be the rate-controlling step.

塩化第二鉄水溶液中における硫化第一鉄の酸化反応

Kinetic study of the oxidative leaching of synthetic ferrous sulfides in an aqueous ferric chloride solution was made.The principal results obtained are as follows:(1) A rate equation appliciable to the leaching reaction, in which both the surface area of powdered materials and the concentration of leachant change significantly, was derived.(2) The main leaching reaction of ferrous sulfide is the oxidative reaction forming elemental sulfur, but this reaction is depressed by competitive reaction of acid leaching below pH 1.(3) The oxidative leaching of stoichiometric ferrous sulfide proceedes faster than non-stoichiometric ore.(4) Rate equation for the oxidative leaching of ferrous sulfide with ferric chloride is found to be R=K·A·(Fe3+) and Ea=12.0 kcal/mol (49.98 at % Fe) and 14.5 kcal/mol (46.93 at % Fe)From this, a chemically controlled direct oxidation mechanism is proposed.

Ferric Chloride-Impregnated Silica Gel for Thin-Layer Chromatography of Steroids

Abstract Silica gel G is mixed with an aqueous solution of ferric chloride, and the resulting slurry spread onto glass plates. After spotting, development, and drying, the plates are sprayed with sulfuric acid. Cholesterol, ergosterol, and Δ5-pregnen-3β-ol-20-one produce colored spots (pink-violet, greenish black, and pink-violet, respectively) without further treatment, but some other steroids require heating at 70 °C for full color development. Other colors generated are: estrone, orange; Δ4-androsten-3,17-dione, blue-green; androsterone, light brown; and 5α-androstan-17β-ol-3-one, tan. After prolonged heating at 70 °C, 6-keto-cholestanol produces an orange-brown spot. Color reactions are more reproducible than they are when the ferric chloride is sprayed on the plate.

Effect of Fortification with Iron on Susceptibility of Skim Milk and Nonfat Dry Milk to Oxidation

Iron-fortified nonfat dry milk can be made by mixing with dry ferric ammonium citrate or by spray drying iron-fortified skim milk concentrates (45% total solids). Concentrates can be fortified directly with an aqueous solution of ferric chloride or ferric ammonium citrate (any convenient concentration) or can be prepared from skim milks fortified similarly before pasteurization. Although some skim milks are susceptible to iron-catalyzed oxidation, they are stabilized during the concentration which precedes drying, and this resistance is retained in iron-fortified dry milk. Iron salts can be added in amounts equivalent to 20mg iron/liter skim milk with no adverse flavor effects when iron-fortified dry milk is reconstituted to skim milk or used in the preparation of 2-10 milk. In other food applications of fortified nonfat dry milk the only adverse effect of added iron was an undesirable color shift when it was added to cocoa, tea, or coffee. In rats, iron in iron-fortified milk is nutritionally as available as that in ferrous sulfate.

Sorption of lanthanum(III), cobalt(II) and iodide ions at trace concentrations on ferric hydroxide

The sorption of lanthanum(III), cobalt(II) and iodide traces was studied in dependence on the solid-liquid contact time, pH value and the properties of the carrier (internally or externally formed). The ferric hydroxide carrier was prepared by mixing aqueous ferric chloride and ammonia solutions. The results are discussed in regard to colloidal properties of the ferric hydroxide and mechanisms of sorption.

Raman Spectral Investigation of the Complex Species of Ferric Chloride in Concentrated Aqueous Solution

Raman spectra of concentrated aqueous solutions of ferric chloride were recorded in the spectral range 50 to 500 cm−1. In near-saturated solutions, spectra show a four-line pattern typical of the tetrahedral FeCl4– complex: 390 cm−1 (w); 335 cm−1 (vs, p); 135 cm−1 (w); 110 cm−1 (s). At lower concentrations a new species dominates the spectrum, showing characteristic Raman lines at 318 cm−1 (s, p) and 165 cm−1 (vw). Conventional investigations of spectral changes with concentration of Fe(III) and chloride, coupled with group theoretical arguments, indicate that the stoichiometry of the complex must be FeCl3 or lower. Of the several symmetries that a FeCl3 complex might assume (C2v, C3v, D2h (dimer), and D3h), the D3h trigonal bipyramid structure FeCl3·2H2O with three equatorial chloride ligands and two axial waters is most compatible with the spectral evidence.

Fractography by crack replication

Experimental studies of crack micro-geometry in slow-propagating fractures such as fatigue and stress corrosion are important in the elucidation of crack growth mechanisms. The majority of high resolution fractographic work on metals has been carried out using both scanning and transmission electron microscopy techniques applied to fully-separated fracture surfaces. However, information on little more than the variables of crack surface topography can be obtained in this way. Nielson [1] has used a method of inverse replica preparation for the study by transmission electron microscope of stress corrosion fissuring on the surfaces of stainless steel specimens. This technique is limited by the necessity for a high temperature oxidation treatment and has so far been demonstrated only with small cracks in stainless steels. A method has therefore been developed for the production of accurate inverse replicas of full-size propagating cracks in metals. The scanning electron microscope provides the best means for the examination of these replicas and makes possible the study of the geometries of both crack and crack tip. In practice in the first stage of the replication process, cracks in a stressed specimen are completely filled with a low viscosity thermosetting polymer resin (epoxy biological tissue embedding resins are ideal for this purpose). It is important that liquid contained in stress corrosion cracks be completely removed prior to resin impregnation and a two stage anhydrous methanol wash/vacuum evaporation process is an effective means of attaining this objective. The resin is cured and the specimen then sectioned and polished metallographically before being subjected to a deep chemical or electrolytic etch to remove the metal surrounding the polymer-filled crack. Ideally the etching reagent should dissolve the metal without in any way attacking or disturbing the crack replica. Acidified aqueous ferric chloride solution and bromine in anhydrous methanol have been found to be particularly suitable as etchants for brass and steel specimens respectively. After completion of the etch the specimen is washed, dried with extreme care and vacuum plated for SEM examination. The extreme fragility of most replicas, particularly in the crack tip regions, increases the difficulty of these operations if damage is to be prevented. The disruptive effects of fluid

Studies on the changes in electrical conductivity and pH during slow coagulation of ferric, chromium and aluminium tellurate sols by electrolytes

The changes in pH and electrical conductivity of ferric tellurate, chromium tellurate and aluminium tellurate sols during their slow coagulation in the presence of KCl, K2SO4 and K3Fe(CN)6 have been studied in comparison with that of the aqueous solutions of ferric chloride, chromium chloride and aluminium chloride acting as the dispersion medium (the socalled intermicellar liquid), being of the same conductance as that of the respective sol. On adding the electrolyte, the maximum changes in conductance and pH have been observed to occur immediately indicating that the phenomena like ion-exchange, adsorption or surface neutralisation during the slow coagulation are instantaneous processes.

Paramagnetic and Electric Quadrupole Hyperfine Interactions of Ferric Ions in Ice and FeCl3·6H2O

Mössbauer resonance in 57Fe has been used to study the species Fe(H2O)5Cl2+ and Fe(H2O)63+ in frozen aqueous solutions of ferric chloride and ferric nitrate. The spectral lines display pronounced broadening as the temperature is lowered, as a result of paramagnetic relaxation effects. In dilute samples at 4.2°K, resolved paramagnetic hyperfine structure was observed for both species and permitted identification of the lowest crystal-field states of the ferric ion. The effective magnetic fields originating from the | ± 52〉 Kramers doublets were determined as 553 kG in Fe(H2O)5Cl2+ and 588 kG in Fe(H2O)63+. The latter ion showed no evidence of an electric quadrupole interaction, whereas the former exhibited a significant quadrupole splitting due to the coordinated Cl− ligand. The apparent electronic relaxation in the pentaquo–chloro complex was found to be substantially faster than that in the hexaquo complex, which may be indicative of a smaller zero-field splitting in the former case or an unbalanced spin pairing in the Cl ion. Results are presented for crystalline FeCl3·6H2O, in which the ion Fe(H2O)4Cl2+ exists as a structural unit. These spectra exhibit unusual line shapes and temperature variations which can be qualitatively understood by considering the effects of paramagnetic relaxation on the hyperfine interactions. The study of FeCl3·6H2O and its frozen solutions also demonstrates that common features as well as differences between the ion complex in solution and in the salt crystal may be inferred from a comparison of the Mössbauer spectra.

Electron Microscope Study of the Morphology of Lithium Fluoride Surfaces following Dissolution in Dilute Aqueous Solutions of Ferric Ions

High-resolution replica electron microscopy has revealed a complex structure of surface ledges on {100} cleavages of lithium fluoride crystals after etching in dilute aqueous solutions of ferric chloride. Ledge heights vary from approximately 400 Å in etchant containing 0.1 ppm ferric ions and are unresolvable at greater than 2 ppm ferric ions. The ledge density is also modified with change in ferric ion content, and this has been related to previous studies of inhibitor adsorption in this system. It is proposed that the ledge structure is due to irregular inhibition by the ferric ions, and the results have been compared with recent theoretical and experimental studies of crystal dissolution.

Electron-microscopic investigation of the formation of colloidal beta FeOOH during slow hydrolysis of an aqueous ferric chloride solution at room temperature

The occurrence and the morphology of spindle-shaped particles of colloidalβ-FeOOH, formed by slow hydrolysis of the aqueous solution of FeCl3 at the room temperature, have been examined by electron microscope.