New methods for separation and determination of actinides, widely used in analysis of actinides in technological and environmental samples are reviewed. Special attention is paid to obtaining and stabilizing transplutonium elements. (TPE) in extreme oxidation states. Their use in analytical practice resulted in expanding possibilities of methods for separation and determination of TPE. Solvent extraction, sorption and extraction chromatography are the basic methods for separation of TPE. Solvent extraction, sorption and extraction chromatography are the basic methods for separation of TPE. Methods of separation in gas phase and some other methods such as precipitation and coprecipitation are applied, however, to a lesser degree. Trends of development of these methods including those of various types of membrane extraction that succeeded in separation of TPE in both trivalent and other valence states have been shown. Attention is paid mainly to consideration of modern methods for determination of actinides, special distinction of such methods being low limits of determination, high precision and selectivity. Alpha- and beta-spectrometric methods with semiconductor detectors are the most advanced among various methods based on registration of nuclear radiation. Tremendous success has been achieved in development of emission-spectrometric methods for determination of trace amounts of actinides and various impure elements occurring in samples of actinides. Sensitive mass-spectrometric methods are widely used for determination of both isotope composition and content of elements in various samples including those which are highly radioactive. More simple and precise titrimetric methods based on using oxidizing-reducing or complexing agents are developed successfully. A large number of coulometric methods for determination of americium and berkelium, characterizing high precision and selectivity as well as luminescence methods have been developed.
This paper desribes the main sources of radioactive contamination of Russia and some techniques elaborated in the V. I. Vernadsky
Institute of Geochemistry and Analytical Chemistry for the determination and speciation of radionuclides in the environment.
Data on radioecological monitoring of the zone affecting by Production Association “Mayak” are presented as example of the
use of these techniques. Some problems of the calculation of radionuclide migration coefficients and the determination of
their so called geochemical forms of occurrence are discussed.
Authors:M. Litvina, M. Milyukova, and B. Myasoedov
The oxidation of americium in HNO3, H2SO4 and HClO4 solutions by a mixture of potassium persulfate with silver salt in the presence of potassium phosphotungstate has been investigated. The influence of acid and its concentration, of (NH4)2S2O3, K10P2W17O61 and silver salt on Am(III) oxidation rate, yield and stability of Am(IV) and Am(VI), has been studied. The complexation of Am(III), Am(IV) and Am(VI) with phosphotungstate ions has been investigated. It has been established that Am(III) and Am(IV) form ML2 complexes and their apparent stability constants have been estimated. The oxidation mechanism is discussed. A method for preparing of Am(IV) in 0.1–6M HNO3, O.1–3M H2SO4, 0.1–1M HClO4 solutions is proposed. The oxidation of Am(III) to Am(IV) by KBrO3 and K2Cr2O7 in HNO3, H2SO4, HClO4 solutions in the presence of K10P2W17O61 has been investigated.
Authors:M. Milyukova, N. Varezhkina, and B. Myasoedov
Extraction of trivalent lanthanides and actinides by primary amines from nitric acid solution in presence of potassium phosphotungstate (K10P2W17O61) has been investigated. The effect of nitric acid, potassium phosphotungstate and extractant concentrations, of the organic solvents and the length of primary amine alkyl chain has been studied. Primary amines in chloroform can be used for separtion of lanthanides and actinides and their group isolation.
Authors:N. Molochnikova, V. Frenkel, and B. Myasoedov
Extraction of actinides has been examined in two-phase aqueous systems based on poly(ethylene glycol) (PEG) from sulfate solutions in the presence of potassium phosphotungstate, which forms strong complexes with ions of tri- and tetravalent transuranium elements. Extraction of these complexes by aqueous PEG solution is complete in contrast to that of penta- and hexavalent actinides. Conditions have been chosen for the separation of actinides in different oxidation states.
Authors:N. Kremliakova, K. Barsukova, and B. Myasoedov
Behaviour of transplutonium and rare-earth elements on TVEX, containing TBP, HDEHP, mixture of TBPHDEHP (11), PAPNA and TOA has been studied. The analytical possibility of isolation and separation of tetravalent Pu and Bk from trivalent actinides and lanthanides from strong nitric acid solutions (1.0–12.0) on TVEX with TBP, POR, HDEHP and TOA has been demonstrated. The separation of trivalent Bk, Cf and Eu from Am and Cm is real on TVEX, containing HDEHP and mixture of TBPHDEHP.
Authors:M. Milyukova, N. Varezhkina, and B. Myasoedov
Extraction of trivalent rare earth elements by a high molecular weight primary amine /decylamine/ from 0.5–3M nitric acid solutions, containing potassium phosphotungstate /K10P2W17O61/, has been investigated. The effect of nitric acid and potassium phosphotungstate concentration of the organic solvent, and lanthanides ionic radii upon distribution coefficients has been studied. It has been established that decylamine solutions in chloroform can be used for the group isolation of rare earth elements and for their separation.
Authors:S. Sin'kov, Yu. Sapozhnikov, and B. Myasoedov
The interaction of short-lived Rn-daughter products /SLDP/, viz.214Pb and214Bi dissolved in sea-water with Fe/III/ hydroxide colloids followed by flotation of combined Fe-SLDP particles at the sea-air interface subsequently generating marine aerosols enriched in214Bi and214Pb have been studied under laboratory conditions. Rate constants for attachment of214Bi and214Pb to dispersed Fe/III/ colloids in the sea water are found to be 3.7×10–4 min–1 litre [g/Fe/]–1 and 2.4×10–4 min–1 litre [g/Fe/]–1, resp., /20°C/ over the concentration range of iron /III/ from 8 to 120 g liter–1. The suggested mechanism of colloid flotation and aerosol generation might be responsible for some peculiarities of SLDP distribution in the lower marine atmosphere.