Radium sorption from pure and slightly contaminated groundwater onto limonite-rich turonian sandstone is characterized by relatively low distribution ratios (60-180 mL/g). When contacted with mine water, the sorption was enhanced by more than 20-fold compared to the pure and contaminated groundwaters. For the typical lime marl, the strongest sorption occured from the groundwater (390-520 mL/g) and a slightly reduced sorption took place from the acidic mine water.
In addition, the radium sorption was studied as a function of the Ba2+ and SO42- concentration. The results were discussed in terms of the ion product and the solubility product. Conclusions were drawn regarding the predominant sorption mechanisms: coprecipitation, surface complexation and ion exchange.
The long-term migration behaviour in the aquifers of the south-east Saxon Elbe basin was calculated on the basis of Hadermanns' equation, considering convection, dispersion, retardation and radioactive decay.
]]>The evaluation of the pH titration curves was carried out with the classical theory of stepwise complex formation, analyzing Bjerrums formation function [1] and by non-linear fitting of the pH titration curve with Sayces multi-equilibria program "SCOGS" [2], considering hydrolysis and mixed-ligand complexation.
In the case of protocatechuic acid, a series of very stable (1:1) to (1:3) complexes are formed (log ß: 14.8/25.9/33.2). The constants calculated by Bjerrums formation function are in full agreement with the values of the SCOGS curve fitting, i.e. U(VI) hydrolysis is surpressed in the presence of this ligand. The complexes with ferulic acid and vanillic acid have a much lower stability: log ß11 values are to 6.88 and 7.16, respectively. In the case of ferulic acid, the assumption of the acidic species [UO2H(fer)]+ with log ß111 =11.9 improves the pH curve fit. Vanillin as complexant leads to pH curves that can be best fitted with the species [UO2(van)]+ and [UO2(van)2(OH)2]2- with log ß values of 4.47 and -3.95, respectively.
Using these data speciation calculations for some calcite-rich mine waters show that the strong U(VI)-carbonato complexes predominate. Under certain conditions only protocatechuic acid complexes can be formed.
]]>Die Methode Verfahren PET wurde zur Untersuchung von Zweiphasenströmungen gasförmig / flüssig angewendet. Inhalt des Vortrages sind die Darstellung von Ergebnissen der Messung des Dispersionskoeffizienten in einer turbulenten Blasenströmung und die Vorstellung geplanter Anwendungen dieser Tracertechnik in einem derzeit in Aufbau befindlichen PET-Tomographen für Schaumuntersuchungen.
]]>Die Methode Verfahren PET wurde zur Untersuchung von Zweiphasenströmungen gasförmig / flüssig angewendet. Inhalt des Vortrages sind die Darstellung von Ergebnissen der Messung des Dispersionskoeffizienten in einer turbulenten Blasenströmung und die Vorstellung geplanter Anwendungen dieser Tracertechnik in einem derzeit in Aufbau befindlichen PET-Tomographen für Schaumuntersuchungen.
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