Ion flotation of lanthanum(III) and holmium(III) from nitrate and nitrate-chloride media

Ion flotation of lanthanum(III) and holmium(III) from nitrate and nitrate-chloride solutions with sodium dodecyl sulfate was studied. The distribution coefficients and their dependence on pH were determined.     

Kinetics of phenol oxidation with iron-manganese concretions

Kinetics of oxidation of phenols on the iron-manganese concretions in the temperature range 293?C353 K at pH 5.5±0.5 was studied. Reaction of oxidation on the iron-manganese concretions has the second order by phenol. It is characterized by low activation energy, 17.5 kJ mol^?1, due to the catalytic action of iron(III) oxide. Lower rate of oxidation of phenols on the iron-manganese concretions is observed as compared to oxidation on the pyrolusite surface. It occurs because of the decrease in MnO₂ concentration in the ironmanganese concretions.     

Thermodynamics of the sorption of cerium complex compounds on anionite

Sorption of cerium in the form of complexes with Trilon B (EDTA) from acid media at pH 3 using weakly basic anionite D-403 in nitrate, chloride, or sulfate forms is studied. The equation of the mass action law is linearized for ion exchange reactions, allowing us to calculate the limiting sorption of ethylenediaminetetraacetate cerate (EDTA cerate) ions on anionite and the constants of the exchange of complex cerium ions by chloride, nitrate, and sulfate ions. The limiting sorption of EDTA cerate ions in the anionite phase transitioning to the sulfate form is lower than that of ions on nitrate or chloride anionite, due to the high ionic potential of the sulfate ions. A sorption series of EDTA cerate ions on anionite D-403 in different ion exchange forms is presented according to the Gibbs energy of the ion exchange equilibrium.     

Effect of chlorides on cerium(III) and samarium(III) ionic flotation

The ionic flotation of cerium(III) and samarium(III) from nitrate solutions with sodium dodecylsulfate as a collector and sodium chloride addition was studied. Dependences of distribution coefficients and a separation factor on the aqueous phase pH at various concentrations of chloride ions were determined.     

Isolation of Rare Earth Element's Radionuclides from Phosphoric Acid Solutions on Cerium (III) Phosphate

Abstract

The isolation of the lanthanide phosphates by crystallization from the solutions of phosphoric acid with the concentration of 2–5 mol·dm^?3, produced during destruction of the apatite, was investigated. The kinetic parameters of crystallization of the lanthanide phosphates and the values of their solubility in phosphoric acid with various impurities under temperatures between 60–90°C have been obtained from the data on distribution of Ce¹⁴⁴ and Eu^152–154 radio- nuclides between the solution and the solid phase. The wide region of supersaturated solution metastability has been determined. The possibility to remove supersaturation in the metastable region by introduction of the cerium (III) phosphate seeds has been proved. Separation of the lanthan-ides from calcium and other accompanying elements in the apatites by crystallization of the phosphates on the CePO₄ ·0.5H₂O seed in the region of small supersaturation of strongly acid solutions has been studied. Calcium phosphate demonstrates the “salting out” effect on the lanthanide phosphates. By thermodynamic computations the ionic compositions of the produced solutions from breaking down the apatite and the solubilities of the lanthanide phosphates were obtained, which agrees with the experimental data. The distribution coefficients for the solid phase and the liquid phase are 1.1.10⁴ for cerium and 4–10³ for europeum. The lanthanides/calcium separation coefficient is 1.3·10³.     

Kinetics of oxidation of phenol with manganese dioxide

The kinetics of oxidation of phenol with manganese dioxide at pH 5.5±0.5 were studied. In the temperature range from 393 to 323 K the reaction is of second order, and it occurs in the kinetic mode with an energy of activation of 42.0 kJ/mol. In the temperature range from 333 to 353 K the reaction follows first-order equation and is controlled by external diffusion; the energy of activation is equal to 6.65 kJ/mol. The oxidation products are hydroquinone and 1,4-benzoquinone, the fraction of the latter being less than 10 mol %.     

Sorption thermodynamics of cobalt(II) cations on iron-manganese concretions

Isotherm of ion exchange of Co²⁺ and Na⁺ cations on iron-manganese concretions is thermodynamically described using a modified Langmuir equation. The thermodynamic characteristics of the ion exchange are determined.     

Sorption of aluminate from alkaline solutions on D-403 anion exchanger

The sorption of aluminate from alkaline solutions on D-403 anion exchanger is studied. The sorption isotherm is described by the Langmuir and Freindlich classical equations and the Redlich-Peterson generalized equation. Thermodynamic parameters of sorption are determined using the Langmuir equation, modified to describe ion-exchange eqiulibria. A method for determining the type of the sorbed ion in the solid phases is proposed.     

Determination of the Surface Area of Minerals by Sorption of Methylene Blue and Thermal Desorption of Argon

The specific surface area of a number of natural aluminosilicates was determined by the methods of thermal desorption of argon and limiting sorption of Methylene Blue. The correlation between the results obtained using these two techniques was discussed.