Sorption extraction of lanthanides from phosphoric acid solutions

The possibility of sorption extraction of lanthanides from nitric-phosphoric and phosphoric acid solutions with inorganic sorbents based on hydrated titanyl hydrophosphate was studied. New technological solutions were suggested for lanthanide sorption from the products which are formed in processing of the Khibiny apatite concentrate on mineral fertilizers (frozen nitric-phosphoric acid extract, a product of nitric acid decomposition of apatite, and the production phosphoric acid from the dihydrate process).     

Recovery of lanthanides from extraction phosphoric acid produced by the dihydrate process

Variant of precipitation of a concentrate of lanthanides from the extraction phosphoric acid formed in the dihydrate processing of the Khibiny apatite concentrate by introduction of sulfuric acid and sodium compounds into the acid is suggested. The main components of the concentrate are double sulfides of lanthanides with sodium, calcium sulfate dihydrate, and sodium hexafluorosilicate. The efficiency of recovery of lanthanides into the concentrate was studied in relation to a sodium compound used.     

磷酸三丁酯萃取脱硫废液中硫氰酸根的初步研究

焦炉煤气含污染物H_2S 5g/m~3-8gm~3、HCN1g/m~3-2.5g/m~(3[1]),目前主要用催化氧化-氨水吸收法(NH_3-OMC)工艺处理.由此产生的脱硫脱氰废液中主要含有NH_4SCN、(NH_4)_2S_2O_3等无机盐,其中,SCN~-及S_2O_3~(2-)浓度均影响脱硫催化剂的效率,规定其总浓度不得超过250g/L.     

Solvent extraction of pertechnetate with TBP from perchloric acid solution

Solvent extraction mechanism of pertechnetic acid with TBP from perchloric acid solutions is discussed. When cyclohexane is used as a diluent of TBP, perchloric acid can be extracted in the form of HClO₄(TBP)₂ into the organic phase. The TBP extraction of pertechnetic acid competes with perchloric acid and its equilibria are expressed as follows: HTcO₄+3TBPHTcO₄(TBP)₃ and HTcO₄(TBP)₃+TBPHTcO₄(TBP)₄.     

Influence of the temperature on the extraction of some lanthanides with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5

The extraction of Pr, Gd and Yb with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) diluted in CHCl₃, C₆H₆, and CCl₄ at 288 K, 298 K, 308 K, and 318 K has been investigated. A compound of the typeMe(PMBP)₃HPMBP is formed in the organic phase. The values of the thermodynamic constants as well as of the parameters H°, S° and G° have been determined.

---

Der Temperatureinfluß auf die Extraktion einiger Lanthaniden mit 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolon

Zusammenfassung Es wurde die Extraktion von Pr, Gd und Yb mit 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolon (HPMBP) in CHCl₃, C₆H₆ oder CCl₄ als verdünnendes Lösungsmittel bei 288 K, 298 K, 308 K und 318 K untersucht. Es wird eine Verbindung des TypsMe(PMBP)₃HPMBP in der organischen Phase gebildet. Die thermodynamischen Konstanten und auch die Parameter H°, S° und G° wurden bestimmt.

     

Thermodynamics of thiocyanate complexes of trivalent actinides and lanthanides

The thermodynamic parameters ΔF, ΔH and ΔS of the complexes of Cm(III), C(III) and Tm(III) with the SCN^? ion have been determined at 30°C in ammonium ion medium of unit ionic strength by the temperature variation method. It has been concluded that both the thiocyanate complexes of trivalent actinides and lanthanides are predominantly inner-sphere type. The higher stability of the second complexes of trivalent actinides is reflected either in the enthalpy or the entropy change depending on the degree of hydration of the trivalent actinide ions. The implications of the greater free energy change for PuSCN²⁺ as compared with other trivalent actinide or lanthanide first thiocyanate complexes are discussed.     

Effect of radiolysis products of di-(2-ethylhexyl)phosphoric acid upon the extraction of lanthanides

In order to clarify the influence of radiation degradation of DEHPA upon the extraction of lanthanides, the extraction of neodymium(III) was studied using DEHPA, MEHPA, 2-ethylhexanol and γ-ray irradiated DEHPA. The most significant effect of DEHPA radiolysis on the extraction was found to be the enhacement of extraction capability mainly due to the primary radiolysis product MEHPA. 2-Ethylhexanol, another radiolysis product, showed a depressant effect on DEHPA-Nd(III) extraction. However, the mixture of MEHPA and 2-ethylhexanol improved the extraction. The mixed solvent DEHPA-MEHPA was found to be more effective than the individual components for lanthanide extraction.     

Temperature effect on the solvent extraction of some lanthanides with thenoyltrifluoroacetone

The solvent extraction of Pr, Gd and Yb with thenoyltrifluoroacetone solutions in C₆H₆, CHCl₃ and CCl₄ at 288 K, 298 K, 308 K and 318 K has been investigated. The values of the equilibrium constant have been calculated as well as the values of the thermodynamic parameters H, S and G. The temperature effect on the solvent extraction of lanthanides with thenoyltrifluoroacetone is discussed.

---

Einfluß der Temperatur auf die Extraktion einiger Lanthanoide mit Thenoyltrifluoraceton

Zusammenfassung Es wurde die Extraktion von Pr, Gd und Yb mit Lösungen von Thenoyltrifluoraceton in C₆H₆, CHCl₃ und CCl₄ bei 288 K, 298 K, 308 K und 318 K untersucht. Es wurden die Gleichgewichtskonstanten für die untersucht3n Metalle, Lösungsmittel und Temperaturen sowie die Werte der thermodynamischen Parameter H, S und G berechnet. Der Einfluß der Temperatur auf die Extraktion von Lanthaniden wird diskutiert.

     

Separation of trivalent actinides from lanthanides by solvent extraction

A method is presented for separating the trivalent actinides, mainly Am and Cm, from trivalent lanthanides by the use of only two solvent extractants. The first solvent removes the heavy lanthanides, leaving the Am, Cm and the lighterlanthanides; the second removes the Am and Cm. Because additional complexing agents are not required, waste-disposal and corrosion problems are reduced. Overall separation factors may be as high as several thousand for the separation of Am and Cm from lanthanides in the fission waste products from reactor fuel processing.     

Separation of thorium from lanthanides by solvent extraction with ionizable crown ethers

Thorium and the lanthanides are extracted by alpha-(sym-dibenzo-16-crown-5-oxy)acetic acid and its analogues in different pH ranges. At pH 4.5, Th is quantitatively extracted by the crown ether carboxylic acids into chloroform whereas the extraction of the lanthanides is negligible. Separation of Th from the lanthanides can be achieved by solvent extraction under this condition. The extraction does not require specific counteranions and is reversible with respect to pH. Trace amounts of Th in water can be quantitatively recovered using this extraction system for neutron activation analysis. The nature of the extracted Th complex and the mechanism of extraction are discussed.     

Synergistic extraction of americium with MEHPA-DEHPA mixed solvent from nitric acid solution

The synergistic effect of the MEHPA-DEHPA mixed system was examined for the extraction of Am(III) from nitric acid solution. Addition of DEHPA or 2-ethylhexanol in MEHPA results in a deleterious effect at MEHPA concentrations lower than 2·10⁻²M but an enhancing effect at higher concentrations. At DEHPA to MEHPA mole ratios of 2 to 4 in moles, the mixed solvent shows a Df for Am which is 1000 times higher than that of DEHPA.     

Determination of lanthanides with m-toluidinyloxamic acid

m-Toluidinyloxamic acid is shown to be about as efficient as the para isomer as a gravimetric reagent for La, Pr and Nd. Conditions have been established for the determination of these lanthanides in presence of a number of metal ions.     

Liquid-liquid extraction of cobalt thiocyanate with trhsooctylamine

Cobalt forms a coloured complex with triisooctylamine and thiocyanate in carbon tetrachloride. The green organic phase has maximum absorbancc at 627.5 mμ and Beer's law is obeyed in the range 0–10 mg Co. The molar extinction coefficient is 1895. The distribution coefficient at room temperature is 5.6. A composition of the coloured species is proposed.     

Effect of sulfuric acid and sodium cations on the solubility of lanthanides in phosphoric acid

Effect of introduction of sulfuric acid and sodium cations into phosphoric acid at 70°C on the solubility of lanthanides was studied.     

Trends in separation factors for the lanthanum series as obtained in solvent extraction from an aqueous thiocyanate solution

Liquid-liquid distribution of all 15 elements in the lanthanum series has been studied using di(2-ethylhexyl) phosphoric acid and tri-n-butylphosphate in n-octane and Adogen 464 in 10% n-octanol-90% n-octane as organic phases and 1 M ammonium thiocyanate as aqueous phase. Appropriate radioactive isotopes of the elements were used as indicators in the determination of the distributions. The great variation in the shape of the curves for separation factors vs atomic number, Z, is discussed in terms of ionic radius, coordination or solvation numbers and the nephelauxetic ratio change as visualized in the Siekierski-effect.     

Studies on extraction of indium by tributyl phosphate from thiocyanate solutions

Indium can be quantitatively separated from a large number of elements which are usually associated with it, by extraction with 15% tributyl phosphate solution in kerosene from hydrochloric acid (pH 1)/0.5M potassium thiocyanate medium and stripping with 6M nitric acid. The equilibration takes 20 min.     

Studies on the solvent extraction of technetium from thiocyanate solutions in mineral acids

Technetium-99m, separated from fission molybdenum-99, has been studied as a component of liquid-liquid phase distribution equilibria. 5-(4-Pyridyl)nonane in a carrier diluent, benzene, has been used to study the distribution of the nuclide from thermodynamically suitable aqueous phases of electrolytes with and without sterically receptive thiocyanate ions. Efficient extraction of the metal can be accomplished in a variety of aqueous phase compositions. The separation factors with respect to molybdenum, under certain experimental conditions, are fairly high. The data have been utilized to effect clean separations of technetium from molybdenum.     

Effect of the nature of diluent on the extraction of beryllium by Aliquat 336 thiocyanate

The extraction behaviour of beryllium from HCl-KCNS by Aliquat 336, a quaternary ammonium halide, in various diluents is described. The dependence of extraction on thiocyanate concentration, pH of aqueous phase, metal and extractant concentrations, has been investigated. Extraction mechanism is suggested on the basis of results obtained.