Authors:A. Saxena, R. Tomar, M. Murali, and J. Mathur
The sorption of 241Am, 233U and 137Cs from nitric acid solutions on a synthesized sodium potassium fluoro-phlogopite (SPFP) gel, structurally close to the fluorine mica mineral, has been studied. The synthesized gel was characterized by energy dispersive spectrometry, X-ray powder diffraction pattern, FTIR and thermogravimetric analysis and has a composition of Na0.5K0.5Mg3(Si3AlO10)F2.6H2O. Different parameters like contact time, acid concentration, amount of SPFP, metal ion concentrations, effect of competing cations, desorption of the nuclides from the loaded SPFP gel etc., were studied using batch technique. Also, the SPFP gel was loaded with Eu(III), U(VI) and Cs(I) and the amounts sorbed on the gel has been estimated by difference from the concentrations in the original solution and those remaining in the solution after loading. Na, K, Mg, Eu and U were estimated by ICP-AES and Cs by electrothermal atomization atomic absorption spectrometry. The exchange of Na, K and Mg with the loaded cations has been evaluated and discussed in the light of ion exchange and surface precipitate sorption mechanisms.
Authors:F. El-Sweify, R. Shabana, N. Abdel-Rahman, and H. Aly
The distribution of UO
, Ce3+ and Am3+ between Chelex-100 and 0.2 and 5.0M ammonium thiocyanate solutions of different hydrogen ion concentrations has been investigated. The results obtained are compared with parallel experimental results using the anion exchanger Dowex-1×4 and the cation excharger Dowex-50×8. It is found that Chelex-100 can act as anion exchanger at pH<2 and as cation and chelate exchanger at higher pH. A main feature of the distribution results of UO
, Am3+ and Ce3+ with Chelex-100 is the very high distribution coefficient for the three cations at pH higher than 3.5 from aqueous solutions containing 0.2 or 5.0M ammonium thiocyanate.
Authors:T. Mori, H. Suganuma, M. Yanaga, and I. Satoh
The formation constants of thiocyanate complexes of Eu(III) and Am(III) in trace concentrations were investigated in mixed
solvent (CH3OH+H2O) solutions of different ionic strength. Furthermore, in paper electrophoresis, the moving velocities of the species of Eu(III)
and Am(III) were investigated in 1.1M (H, Na)(SCN, ClO4) mixed solvent (CH3OH-H2O) solutions. The results showed that the difference between the velocities of Eu(III) and Am(III) is explained by the difference
of the mean charges calculated by the formation constants of thiocyanate complexes of Eu(III) and Am(III) in the solution.
The Am(III) adsorption from very dilute aqueous solutions on polyethylene was studied as a function of the pH value, the composition of dissolved salts and the presence or absence of adsorbent SiO2. It was found that the Am(III) adsorption on polyethylene is decreased with increasing H+ concentration and dissolved salt concentrations and in the presence of SiO2 as an adsorbent. The mechanisms of Am(III) adsorption on polyethylene were discussed. Based on the observations in this paper, extreme care is necessary to minimize and correct the Am(III) adsorption on the container walls in order to improve the accuracy of Am(III) distribution coefficient (Kd) between a solid and an aqueous solution.
Authors:T. Sakuragi, S. Sawa, S. Sato, T. Kozaki, T. Mitsugashira, M. Hara, and Y. Suzuki
In the wide pH range of 4 to 10, distribution ratios of Am(III)-humate species to free Am(III) ions (DAmHA = [Am(III)HA]/[Am(III)]free) were determined at 10 ppm (4.7 . 10-5 eq/dm3) of humic acid and 0.1M NaClO4 by a cation-exchange equilibrium method under N2 atmosphere. The DAmHA was insensitive to an increase in pH (logDAmHA ≈ 2.6-2.8), which indicates the formation of mixed hydroxo-humate complexes. The present DAmHA value is larger than the estimated value from available stability constants for ternary complexations by spectroscopic analysis (1.4-2.1) and is markedly smaller than that of Eu(III) obtained by the dialysis method (3.7-8.0) reported in the literatures. The DAmHA obtained in the present study is widely applicable to estimate the actinide(III) and lanthanide(III) sorption on minerals in the presence of humic and fulvic acids.
Authors:S. Travnikov, E. Fedoseev, A. Davydov, and B. Myasoedov
Separation of239Np from243Am including extraction of Np/IV/ and Am/III/ by thenoyltrifluoroacetone solution in benzene, transformation of thenoyltrifluoroacetonates into volatile hexafluoroacetylacetones in the flow of a carrier gas saturated with hexafluoroacetylacetone vapours are described.
Authors:H. Yang, E. Lee, J. Lim, D. Chung, and K. Kim
The extraction of Am(III) and Eu(III) using a γ-pre-irradiated N,N′-dimethyl-N,N′-dibutyltetradecyl malonamide (DMDBTDMA)
modified with N,N′-dihexyloctanamide (DHOA) in n-dodecane (NDD) at 4.5M HNO3 has been studied as a function of the absorbed dose up to 2×106 Gray. The distribution ratios of Am(III) and Eu(III) were almost constant until a dose of 1×105 Gray and then they decreased gradually up to a dose of 2×106 Gray. The decrease of the distribution ratios of Am(III) and Eu(III) are due to the decreasing concentration of the DMDBTDMA
by a γ-pre-irradiation and these results were supported by a determination of the DMDBTDMA concentration with a gas chromatography
method. The distribution ratios of Am(III), Eu(III), Ce, Nd and Y with γ-pre-irradiated (DMDBTDMA-DHOA)/NDD have also been
studied as a function of the nitric acid concentration and the extraction temperature.
The extraction behaviour of Ce(III) and Am(III) in extraction chromatography has been investigated on the basis of partition and infrared studies. The stationary phase was purified undiluted DHDECMP supported on Amberlite XAD-4 and the mobile phase was nitric acid. The results have shown that the equilibria for the extraction of Ce(III) and Am(III) by the DHDECMP/XAD-4 resin agreed very closely with those in solvent extraction.
A simple, rapid method has been developed for the sequential separation of actinide elements from samples with high salt content such as those resulting from efforts to characterize Hanford storage tank waste. Actinides in 9M HCl solution are introduced into an anion exchange column. U(VI), Np(IV) and Pu(IV) are retained on the column while Am(III) passes through. Plutonium is eluted first, reductively; after which neptunium and then uranium are eluted with mixtures of HCl and HF. The Am(III) is purified by cation exchange in a nitric acid system.