Selective separation and extraction of copper(II), iron(II,III), and Cerium(III,IV) ions from aqueous solutions by electroflotation method

Possibility of the electroflotation separation and extraction of cerium(II, IV), copper(II), and iron(II, III) from aqueous solutions is demonstrated. The optimal pH value and the concentration ratio of ions of the metals being separated, at which their electroflotation separation and extraction from aqueous solutions is the most efficient, was determined. It was shown that the electroflotation method is promising for selective separation and extraction of metal ions with various hydrate-formation pH values from aqueous solutions.     

Effect of binary solvent composition on phenol extraction from aqueous solutions

Partition factors D between an apolar solvent-ketone or ketone-ketone binary mixture and water have been determined for a series of p-alkylphenols. The effects of the composition of a binary solvent and phenol hydrophobicity on the partition factor have been studied. Empirical relationships adequately describing the partition factor isotherms versus the mole fraction of the active component of the binary organic solvent have been found and discussed.     

Chitosan membrane: tool for chromium (III) recovery from aqueous solutions

In this study four kinds of Chitosan membranes were prepared. The permeability of the membranes was then investigated by permeation of K+ in these membranes. The performances of the prepared membranes for recovery of chromium (III) from aqueous solution were evaluated. The effects of operation conditions on permeation characteristics were determined, and permeation mechanism was discussed. The stability of the membranes was also studied.     

Physicochemical efficiency of electroflotation of finely divided carbon nanomaterial from aqueous solutions containing surfactants

Electroflotation of finely divided carbon nanomaterials—carbon nanoflakes (CNFls)—from aqueous solutions with a wide pH range of 3.0 to 11.0 in the presence of surfactants of various types was studied experimentally. The efficiency indices were determined for the electroflotation of CNFls from CNFls–surfactant–Na₂SO₄ solutions in the presence of a coagulant (iron(III) chloride) and flocculants, which enabled one to find the optimal conditions for electroflotation of carbon nanomaterials.     

Experimental studies of the efficiency of electroflotation recovery of poorly soluble lanthanum compounds from aqueous solutions

Features of electroflotation recovery of poorly soluble lanthanum compounds from aqueous solutions containing sodium salts were experimentally determined and studied for the first time. The role was identified that anionic, cationic, and nonionic surfactants added to various supporting electrolytes (sulfate, chloride, carbonate, nitrate) play in the efficiency of electroflotation recovery of poorly soluble lanthanum compounds. The possibility of electroflotation recovery of lanthanum hydroxide with an efficiency of 95–99% was experimentally and theoretically substantiated.     

Joint electrolytic deposition of vanadium(V) and chromium(III) oxides from aqueous sulfate solutions

The conditions of the joint electrolytic deposition of vanadium(V) and chromium(III) oxides from mixed sulfate solutions at different concentration ratios of the main components were studied.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 11, 2004, pp. 1795–1798.Original Russian Text Copyright © 2004 by Nagirnyi, Apostolova, Baskevich, Shembel.     

Sorption of phosphate ions on iron(III), zirconium(IV), and chromium(III) oxyhydroxides from aqueous electrolyte solutions

The adsorption of phosphate ions from aqueous solutions with an ionic strength of 0.5 on iron(III), zirconium(IV), and chromium(III) oxyhydroxide hydrogels has been studied as influenced by chloride and sulfate ions. Despite the high concentrations of chloride and sulfate ions, they do not inhibit phosphate adsorption on the hydrogels; they only slightly change the isotherm shape. In the range of equilibrium phosphate concentrations equal to 30–50 mmol/l, all isotherms for iron and zirconium oxyhydroxide gels signify the appearance of a second adsorption layer (two-step isotherms). Both steps are satisfactorily fitted by the Langmuir equation. The maximum adsorptions and adsorption constants have been calculated. For chromium oxyhydroxide gels, the intraduction of an electrolyte dramatically decreases the equilibration rate.     

The extraction of Yb(III) and Lu(III) with chloroform from aqueous solutions in the presence of cupferron

The equilibrium of distribution of Yb(III) and Lu(III) between chloroform and the aqueous phase in the presence of cupferron (the ammonium salt of N-nitrosophenylhydroxylamine) were studied as apH function of the aqueous phase and the concentration of N-nitrosophenylhydroxylamine (HL). The stability constants for theLnL _n ^3–n ) complexes (n=1÷3) being formed in the aqueous phase were established, as well as the equilibrium constants of the extraction reaction $$Ln(H_2 O)_m^{3 + } + 3HL_{(O)} \mathop \rightleftharpoons \limits^{K_{ex} } LnL_{3(O)} + 3H^ + + mH_2 O(Ln^{3 + } = Yb,Lu),$$ two-phase stability constants for theLnL ₃ complexes,pH _0.5 and the separation factor Lu(III) from Yb(III).     

Quantum efficiency of the luminescence of Eu(III), Tb(III) and Dy(III) in aqueous solutions

Summary The luminescence quantum efficiency of Eu(III), Tb(III) and Dy(III) in chloride solutions as well as complexed by aminopolyacetic acids was determined. An interpretation of the observed dependences in the system investigated has been proposed.

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Die Lumineszenz-Quantenausbeute von Eu(III), Tb(III) und Dy(III) in wäßrigen Lösungen

Zusammenfassung Die Lumineszenz-Quantenausbeute von Eu(III), Tb(III) und Dy(III) in Chloridlösung und in Komplexen mit Aminopolyessigsäuren wurde bestimmt. Eine Interpretation der beobachteten Abhängigkeiten im untersuchten System wurde vorgeschlagen.

     

Study of the formation of the dispersed phase in aqueous solutions of Cu(II)

The formation of the dispersed phase in aqueous solutions of Cu(II) in the presence of formate and alcohols is studied using the pulse radiolysis method. The incubation time and the half-life for the formation depend on the absorbed dose and on the number of applied pulses as well as on the solution composition itself (Cu concentration, pH, OH-scavenger etc.). With increasing dose per pulse or number of pulses, the incubation time and the half-life for colloid formation decrease. The nature of the colloids formed is discussed.     

The interpretation of X-ray diffraction by aqueous solutions of aluminum(III) nitrate and chromium(III) nitrate

Aqueous solutions of the nitrates of aluminum (0.5 M) and chromium (0.5 M) are investigated with X-ray diffraction at t = 25° C. The experimental intensity is interpreted in terms of an electron product-function which is a sum of various pair contributions. The contribution containing the information about cationic hydration has been evaluated by combining the results of separate experiments. The method is in several aspects quite different from what is usual. Still the results obtained are in general agreement with the data reported elsewhere. That is, sixfold coordination at 1.90 Å and 1.98 Å and a second shell containing about 12 water molecules appearing at 4.10–4.15 Å and 4.20–4.25 Å for Al³⁺ and Cr³⁺ respectively.     

Homogeneous phase synthesis of chitosan silica hybrid materials in ionic liquid medium and adsorption of Fe(III) from aqueous solutions

Abstract

Two chitosan silica hybrid materials were prepared by a two-step process in 78–84% yields using the homogeneous phase reaction of 3-(triethoxysilyl)propyl isocyanate with chitosan dissolved in 1-n-butyl-3-methylimidazolium chloride ionic liquid (～10% w/w), which was followed by NH₄OH catalyzed hydrolysis of triethoxysilyl groups and then sol-gel process. These new hybrid materials were shown to adsorb up to about 95% of Fe³⁺ from 5?×?10^?4 M aqueous solution at room temperature in 24?h.     

Synergistic extraction of Eu(III) and Nd(III) from aqueous medium using a mixture of sulfasalazine and 1,10-phenanthroline

Journal of Radioanalytical and Nuclear Chemistry - Solvent extraction of Eu(III) and Nd(III) from aqueous medium was investigated by sulfasalazine in benzoyl alcohol as single extractant and then...     

Effect of the anionic composition and pH on the dissolution kinetics of chromium(III) oxide and chromium(III) hydroxide oxide in acids

Based on an experimental investigation of the effects of the pH and anionic composition on the dissolution rate of chromium(III) oxide α-Cr₂O₃ and chromium(III) hydroxide oxide α-CrOOH and subsequent modeling of the process, it is demonstrated that, depending on the pH, the rate-controlling stage of the dissolution is the CrOH²⁺ or CrHSO ₄ ²⁺ sobulization.     

Some aspects of the solvent extraction of Fe(II) and Fe(III) from an aqueous acidic medium containing Cr(III)

The separation of Fe(II) and Fe(III) from an aqueous acidic sulphate medium containing Cr(III) was investigated. It was found that the Fe(II) and Fe(III) can be removed from the aqueous phase using Aliquat 336 thiocyanate as solvent extractant. The Fe(II) is extracted as the Fe(NCS)₄²⁻ species while Fe(III) is extracted as Fe(NCS)₅²⁻ species. The effects of pH, extractant concentration and thiocyanate added to the aqueous phase were investigated.     

Simultaneous determination of chromium(III) and chromium(VI) in aqueous solutions by ion chromatography and chemiluminescence detection.

A method for the simultaneous determination of chromium(iii) and chromium(vi) in a flow system based on chemiluminescence was developed. A Dionex cation-exchange guard column was used to separate chromium(iii) from chromium(vi), and chromium(vi) was reduced by potassium sulfite, whereupon both species were detected by use of the luminol-hydrogen peroxide chemiluminescence system. Linear calibration for both species was established over the concentration range 1-1000 micrograms l-1. The precision at the 20 micrograms l-1 level was 3.5% for chromium(iii) and 3.3% for chromium(vi), respectively. The detection limit was 0.5 micrograms l-1 for both species. Data were in agreement with Zeeman-effect background corrected atomic absorption spectrometry measurements.     

The extraction of Cr(III) from aqueous thiocyanate solutions and its separation from Co(II) and Ni(II)

For the system liquid anion-exchanger—Cr(III)−NCS⁻, an investigation has been made of the dependence of the percentage extraction of Cr(III) on parameters such as standing time of the Cr(III)−NCS⁻ solution, temperature, pH and type of exchanger. Quantitative extraction of e.g. 4·10⁻⁴ M Cr(III) by 0.1M Aliquat in CCl₄ is easily achieved at room temperature, using 4.75M KNCS−0.05N HCl as aqueous phase. At high Cr(III) concentrations, the complex anion present in the organic phase is Cr(NCS) ₆ ³⁻ ; when working with dilute metal ion solutions, the species extracted is Cr(NCS)₄ (H₂O) ₂ ⁻ . Separations of mixtures containing 10⁻²−10⁻⁴ M Co(II), Ni(II) and Cr(III) have successfully been accomplished.     

Coordination compounds of chromium(III) with different complexones and citric acid in aqueous solutions

A spectrophotometric study of heteroligand chromium(III) complexes with iminodiacetic (H₂Ida), N-methyliminodiacetic (H₂Mida), N-(-hydroxyethyl)iminodiacetic (H₂Heida), nitrilotriacetic (H₃Nta), ethylenediaminetetraacetic (H₄Edta), and citric acids (H₄Cit) showed that complexation in ternary systems depends on the concentrations of the reagents and the pH of the medium. The resulting complexes were [Cr(HIda)(H₂Cit)], [Cr(HMida)(H₂Cit)], [Cr(HHeida)(H₂Cit)], [Cr(HHeida)(HCit)]^–, [Cr(HNta)(H₂Cit)]^–, [Cr(HNta)(HCit)]^2–, [Cr(Nta)(HCit)]^3–, [Cr(HEdta)(HCit)]^3–, and [Cr(Edta)(HCit)]^4–. The logarithms of their stability constants are 41.97 ± 0.47, 43.54 ± 0.62, 42.32 ± 0.62, 36.34 ± 0.26, 43.70 ± 0.25, 39.75 ± 0.45, 32.93 ± 1.56, 46.46 ± 0.80, and 41.71 ± 0.81 , respectively (I = 0.1 (NaClO ₄)).Translated from Koordinatsionnaya Khimiya, Vol. 30, No. 12, 2004, pp. 946–950.Original Russian Text Copyright © 2004 by Kornev, Mikryukova.