Search Results
Thermodynamics of dinonylnaphthalene sulfonic acid (HD)
Extraction of trivalent americium, curium and californium
Abstract
The effect of temperature on the extraction of the trivalent actinides Am3+, Cm3+ and Cf3+ with the liquid cation exchanger dinonylnaphthalenesulphonic acid (HD) in toluene is studied. The different thermodynamic functions of this system are determined from the experimental results. It is found that the free energy variation for the extraction of these metal ions by HD is mainly determined by the entropic terms arising from the hydration-dehydration process of the exchanged ions.
Abstract
The temperature dependence of the molar heat capacities of the tellurites CoTeO3, MnTeO3 and MnTe6O13 are determined. By statistical manipulation of the values obtained, the parameters in the equations for the corresponding compounds showing this dependence are determined using the least-squares method. These equations and the standard molar entropies are used to determine the thermodynamic functions for T'=298.15 K.
Abstract
Low-temperature heat capacity of two polymorphs of glycine (α and γ) was measured from 5.5 to 304 K and thermodynamic functions were calculated. Difference in heat capacity between polymorphs ranges from +26% at 10 K to -3% at 300 K. The difference indicates the contribution into the heat capacity of piezoelectric γ polymorph, probably connected with phase transition and ferroelectricity. Thermodynamic evaluations show that at ambient conditions γ polymorph is stable and α polymorph is metastable.
Solvent extraction studies using phosphonic acid monoesters
III. Extraction and determination of stability constants of Eu(III) ethyl hydrogen benzyl and ethyl hydrogen benzoyl phosphonates in n-hexane
Abstract
The extraction of radioactive152–154Eu by ethyl hydrogen benzyl phosphonate (HEBP) and ethyl hydrogen benzoyl phosphonate (HEBOP) in n-hexane from an aqueous solution of ionic strength 0.1M (Na+, HClO4) has been investigated at different temperatures and the thermodynamic functions evaluated. HEBOP was found to be more efficient than HEBP as extractant. In addition, the stability constant of the extracted complexes were determined.
Abstract
The extraction of U(VI) with newly synthesized long chain alkyl amide, N,N-dibutyldodecanamide (DBDA), in toluene has been studied. The dependence of the extraction on nitric acid and DBDA concentrations and temperature from nitric acid solution has been considered. The extracted species has also been investigated using FT-IR spectrometry. The related thermodynamic functions were calculated. The separation factor between U(VI) and Th(IV) is higher and there is no third phase formation under the conditions studied.
Hydroxylamine derivatives in Purex Process
I. Study on the kinetics of redox reaction between N,N-diethylhydroxylamine and nitrous acid
Abstract
The kinetics of oxidation-reduction reaction between N,N-diethylhydroxylamine (DEHAN) and nitrous acid in nitric acid solution have been studied by spectrophotometry at 9.5°C. The rate equation is −d[HNO2]/dt=K[HNO2]·[DEHAN][HNO3] and the rate constantK=12.81 (mol/l)−2·min−1. A possible mechanism has been suggested on the basis of chemical analysis and Raman spectra. The activation energyE and the thermodynamic functions ΔH #, ΔG # and ΔS # are also calculated.
Abstract
It was found that N,N,N,N-tetrabutylsuccinylamide (TBSA) in a diluent composed of 50% 1,2,3-trimethylbenzene (TMB) and 50% kerosene (OK) can extract thorium(IV) ion from a nitric acid solution. The results of the extraction study suggested the formation of a 1
41 thorium(IV) ion, nitrate ion and N,N,N,N-tetrabutylsuccinylamide complex as extracted species. The related thermodynamic functions were also calculated.
Abstract
N,N,N,N-tetrabutylsuccinylamide (TBSA) in a diluent composed of 50% trimethylbenzene (TMB) and 50% kerosene (OK) can extract uranyl (II) ion from nitric acid solution. The results of extraction study suggested the formation of the 1
21 uranyl (II) ion, nitrate ion and N,N,N,N-tetrabutylsuccinylamide complex as extracted specis. The values of thermodynamic functions have been calculated.
Abstract
Extraction coefficients for all lanthanides have been determined in two systems: 0.2M TBP-3M NaNCS, and 3.6M TBP-0.2M NaNCS. The data have been used for the calculation of relative changes in thermodynamic functions accompanying the investigated extraction process. The compensation of enthalpy and entropy changes is found as a result of dehydration of the lanthanide aquaions.
Abstract
The molar heat capacities of the pure samples of acetone and methanol, and the azeotropic mixture composed of acetone and methanol were measured with an adiabatic calorimeter in the temperature range 78–320 K. The solid–solid and solid–liquid phase transitions of the pure samples and the mixture were determined based on the curve of the heat capacity with respect to temperature. The phase transitions took place at 126.160.68 and 178.961.47 K for the sample of acetone, 157.790.95 and 175.930.95 K for methanol, which were corresponding to the solid–solid and the solid–liquid phase transitions of the acetone and the methanol, respectively. And the phase transitions occurred at 126.580.24, 157.160.42, 175.500.46 and 179.740.89 K corresponding to the solid–solid and the solid–liquid phase transitions of the acetone and the methanol in the mixture, respectively. The thermodynamic functions and the excess thermodynamic functions of the mixture relative to standard temperature 298.15 K were derived based on the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature.
