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Abstract  

Standard Gibbs energies of transfer of cesium ion from water to nitrobenzene and nitrobenzene-carbon tetrachloride mixture have been evaluated from electrochemical measurements. From the results the conclusion can be drawn that with increasing dielectric permitivity of organic mixed solvents the value of the Gibbs transfer energy of Cs+ ion decreases.

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Abstract  

Transport of strontium through supported hollow fiber dichlorobenzene liquid membranes has been studied. The possible mechanism of strontium transport with 18-crown-6 ether as a carrier and picrate as co-counter-ion as well as the construction of a pertraction device with on-line radiometric detection of strontium using85Sr tracer is described. Preliminary results of strontium pertraction in a recycling and one-pass mode with different concentrations of crown are shown.

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Abstract  

The use of isotope dilution technique to eliminate problems associated with demands for a high load capacity in column-coupling capillary isotachophoresis was studied. Determinations of phosphate present in a model mixture and in white wine served for the evaluation of this approach to quantitative analysis in isotachophoresis. A high selectivity of the analysis with acceptable accuracy and precision of the determination also in complex ionic mixtures in a short time are obvious advantages of this approach.

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Abstract  

Membrane extraction is treated as an analogue of solvent extraction in three-phase distribution systems. Its advantages and drawbacks are discussed with respect to separation and preconcentration of radionuclides, fission products of uranium and uranium itself.

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Abstract  

A continuous extraction device for preconcentration of metals with light phase internal recycle has been developed. This system was used for preconcentration of cobalt and uranium from 20–30 dm3 samples with 10.8 dm3/hours feed rate. The emulsion membranes were created of surfactants and LIX 64 N (for cobalt) or di-2ethylhexyl-phosphoric acid (for uranium) as a carrier to control stability and permeability for long time periods. The results from continuous extraction of cobalt and uranium using the device constructed have shown the possibility to reach 100–200-fold preconcentration of metals with high yield (min. 92%).

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Abstract  

Radiolytic products of the two-phase systems of nitrobenzene-carbon tetrachloride-water mixtures have been identified using HPLC adsorption chromatography on SEPARON SIX silica gel column under an elution gradient from n-hexane to ethyl acetate. That the product formation is a function of the mixture composition is indicated by the chromatograms. Para-nitrophenol constitutes one of the major radiolytic products in the system where the volume ratio of nitrobenzene is more than that of carbon tetrachloride and its radiation yield is dependent on the volume ratio of the aqueous phase.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
F. Macášek
,
V. Mikulaj
,
P. Rajec
,
R. Čech
,
L. Mátel
,
R. Kopunec
,
J. Kuruc
, and
A. Švec

Abstract  

Radiolytical decomposition of phenol was investigated at60Co gamma irradiation (1–2 Gy·s–1, 10 kGy) of pre- and continuously aerated aqueous solutions at concentrations of phenol 1–100 mg· ·dm–3 and in the presence of sodium hydroxide, sulphuric acid, sodium and ferrous sulphate, formaldehyde, 2-propanol,n-hexane, xylene, benzene, and commercial gasoline. From the decomposition rate at doses 50–400 Gy, a phenomenological model of linear relation between the dose acquired for 37% decomposition (D 37), initial concentration (g·m–3) of phenol (p 0) and of an admixture (s 0) was confirmed in the formD 37=52f tr(p 0+f eq s 0), wheref's are constants which can be attributed to the relative transformation resistance of phenol towards the OH radicals in given matrix (f tr, for pure waterf tr=1) and relative acceptor capacity of competing substrate (f eq). In real wastewaters, the efficient decrease of phenols content may be substantially lower than that in model solutions, obviously due to radiation oxidation of aromates, as proved by irradiation of aqueous solutions of benzene. Technical and economical feasibility of the process is discussed.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
Ľ. Mátel
,
P. Rajec
,
V. Mikulaj
,
A. Švec
,
O. Rosskopfová
, and
L. Drahošová

Abstract  

Specific activity of239,240Pu in contaminated soils from the bank of Manivier channel was determined to be in the range of 5–40 Bq·kg–1 and for soils from the bank of Dudvah river 0.6–8 Bq·kg–1. The ratio of239,240Pu/137Cs found in the samples is about 1·10–4, which is very close to the ratio found in the pulp of high activity concentrate in the collecting tank of nuclear power plants (NPP).

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
A. Paulenová
,
P. Rajec
,
J. Kandráč
,
G. Sasköiová
,
E. Tóthová
,
P. Bartoš
,
V. Švec
, and
R. Góra

Abstract  

Complexation equilibrium of metals by three humic acids of different origin with ultrafiltration method was investigated at pH 4 a 5 and ionic strength I = 0.1M NaClO4. Commercial (Aldrich) and two original humic acids (peat and soil, obtained by six step isolation process from the material from Trnava county, close to the NPP Jaslovské Bohunice) were used in this study. For the evaluation of the results, the model of metal ion charge neutralization upon humic acid functional group proposed by the Kim and Czerwinski was used. Complexation constants were calculated using the terms of this model (operational concentration, loading capacity). The values of log = 5.39±0.16 for yttrium, 6.15±0.16 for americium and 5.20±0.08 for lead were found. Correlation of free metal concentration and ratio of molar fraction of complexing functional groups confirms the validity of charge neutralisation model for metal and polyelectrolyte complexation study.

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