Strontium forms a compound of composition (SrL)2A·nH2O with low solubility (5.0·10–6 mol Sr·dm–3) in the presence of 18-crown-6 (L) and tungstosilicic acid (H4A) in acid media, as has been found by radiometric precipitation titration. Formation of the compound with limited solubility was used for separation of strontium and calcium from 1 mol·dm–3 HCl. It is possible to separate strontium in the range from trace to 6 mmol·dm–3 in the presence of calcium with its concentration up to 0.2 mol ·dm–3 and the recovery determined was 95% of Sr and 5% Ca or 90% of Sr and 4% Ca, respectively. The ratio of Sr/Ca depends on the stability constants ratio of metal-L (⊃SR/⊃ca) in the case of gradual addition of L. Potassium up to the concentration of 0.05 mol·dm–3 does not influence recovery of strontium.
A universal and fast method of90Sr determination in environmental matrices (raw and dried milk, plants, soils) has been elaborated. Solvent extraction method of daughter90Y by tributyl phosphate was used. The method of strontium determination is compatible with determination of other transuranic elements (americium, plutonium) and there is no need to check the chemical yield of strontium.
The transport of strontium cation through a hollow fiber supported dichlorobenzene membrane using 18-C-6 crown ether, nitrate and anion of dinonylnaphtalen sulfonic acid has been studied. A permeation device-single hollow fiber module with on-line radiometric detection of strontium using85Sr tracer was used.
In general, the amount of radiocesium sorbed by the five sorbents with 0.01 mol·dm–3 NaCl was in order zeolite > NiFeCN–SiO2 > montmorillonite > aerogel > silica gel. Addition of humic acid solution to the sorbents depressed the sorption of cesium by all sorbents, except for NiFeCN–SiO2 was not seen, with the greatest effect showing to the aerogel. The presence of humic acid resulted in an enhanced desorption of cesium from zeolite, NiFeCN–SiO2 and to a lesser extent from montmorillonite and silica gel. The order of cesium retention following desorption for both sorbent and sorbent/humic-acid mixtures was zeolit > NiFeCN–SiO2 > montmorillonite > silica gel. The presence of humic acid resulted in decreasing of distribution coefficient values for both sorption and desorption processes.
Separation of thorium, uranium and plutonium by basic tertiary amine, Alamine-336 and neutral organophosphoric extractant tri-n-octylphosphinoxide in xylene and cyclohexane solutions has been investigated. According to results obtained, Alamine-336 was chosen for the extraction of atmospheric precipitation samples. Separation process with tri-n-octylphosphinoxide based extraction can lead to higher chemical yields, but according to our results reproducibility is worse due to incomplete back-extraction of elements from organic phase. Analysis of simulated 1001 sample concentrate has shown significant effect of Ca2+, Fe3+ and Mn2+ ions concentration.
Halogenated hydrocarbon emulsion liquid membranes (e.g. trichlorobenzene) which were stabilized with polyamine tenside, using 18-crown-6 and picric acid as carriers, were applied to separation of strontium and calcium. Application in the separation of Sr/Ca enable us to enhance preconcentration factor for strontium due to decreasing occlusion of freed solution and better hydrodynamic parameters of the emulsion.
A batch pertraction (liquid membrane extraction, MX) of cobalt has been studied, with industrial reagent LIX 64N and ABF (USSR) as a carrier. The influence of cobalt, reagents and acid concentration has been searched. The kinetic and hydrodynamic characteristics of the emulsion were optimized. In one batch pertraction process it is possible to reach 100-fold cobalt preconcentration with 93–98% yield from 1 dm3 sample volume.
The mechanism of palladium extraction by trilaurylamine and trilaurylmethylammonium nitrate from nitric acid solutions was studied. The composition of the extracted compounds was determined by the Job method as well as by organic phase saturation. Both reagents were found to extract palladium as Am2Pd/NO3/4 /Am=ammonium cation/.