Annual Report 2009/2010 - JUWEL - Forschungszentrum Jülich

Hansen, B., Curtius, H., Odoj, R.:
Synthesis of a Mg-Cd-Al layered double hydroxide and sorption of selenium
Clays and Clay Minerals, Vol. 57, No. 3 (2009), 330 – 337.
Leaching experiments with metallic uranium-aluminum research-reactor fuel elements
in repository-relevant MgCl 2 -rich salt brine (brine 2) were performed. A Mg-Al layered
double hydroxide (LDH) with chloride as the interlayer anion was identified as a
crystalline secondary-phase component. In the present study, the incorporation of Cd
into the structure of the Mg-Al-Cl LDH was investigated. Synthesis by a
coprecipitation method was performed and the Mg-Cd-Al-Cl LDH obtained was
characterized. The sorption behaviour of selenium on the LDH was investigated in
water, clay pore-water (Mont-Terri-type), and brine 2. Using a LDH concentration of
10 g/L, the sorption kinetics were rapid and equilibrium was reached within 12 h. The
sorption of selenium decreased with increasing amount of chloride anions in the
solutions. The chloride anions acted as competing anions for the sorption of
selenium. The effect of pH on selenium sorption was investigated and a large buffer
capacity of the LDH was observed. For the range of selenium concentration used,
linear sorption isotherms were obtained which obeyed the Freundlich and Dubinin-
Radushkevich models. From these, the energies of selenium sorption were calculated
to be in the range of ion-exchange processes.
Modolo G., Kluxen P., Geist A.:
Demonstration of the LUCA process for the separation of americium(III) from
curium(III), californium(III), and lanthanides(III) in acidic solution using a synergistic
mixture of bis(chlorophenyl)dithiophosphinic acid and tris(2-ethylhexyl)phosphate
Radiochimica Acta, 98 (2010) 4, 193 - 201
The LUCA process was developed at Forschungszentrum Jülich for the selective
separation of Am(III) from an acidic solution containing the trivalent actinides Am(III),
Cm(III), and Cf(III) as well as lanthanides. A mixture of 0.4 mol/L
bis(chlorophenyl)dithiophosphinic acid and 0.15 mol/L tris(2-ethylhexyl)phosphate
dissolved in 20% isooctane/80% tert-butyl benzene was used as the extractant. The
process was carried out in centrifugal contactors using an optimized flowsheet
involving 7 stages for extraction, 9 stages for scrubbing and 8 stages for backextraction.
Very encouraging results were obtained. A high feed decontamination
factor was obtained for Am(III) (>1000), and recovery in the product after stripping
was higher than 99.8%. The Am(III) product was contaminated with 0.47% Cm(III).
More than 99.9% Cf(III), Eu(III) and >99.5% Cm(III) inventories were directed to the
raffinate and the contamination with Am(III) (