Volume 96, Issue 1 - 1

The solvation of the Eu-perchlorate (ClO 4 – ) and triflate (CF 3 SO 3 – , OTf – ) salts as well as of Cm(ClO 4 ) 3 and Am(ClO 4 ) 3 in the ionic liquid C 4 mimTf 2 N (1-butyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide) has been comparatively investigated by application of laser fluorescence spectroscopy and X-ray absorption spectroscopy. Moreover, the ClO 4 – /OTf – ligand exchange reaction for the two actinide cations has been analyzed by the same spectroscopic techniques. A structural model for the different complexes was determined by the interpretation of the spectroscopic data. The lanthanide and the two actinide cations show the same coordination in C 4 mimTf 2 N. Moreover, a sequence for the strength of complexing ligands could be deduced from the spectroscopic data for the lanthanide and the two actinides: ClO 4 – >OTf – ≥Tf 2 N – >H 2 O.

In the field of nuclear waste management, prediction of the radionuclides migration through the geosphere has to take into account the effects of temperature. The chosen substrate, zirconium diphosphate, was previously described concerning its surface acidity properties for several temperatures (25 °C, 50 °C, 75 °C, 90 °C). Edges for uranyl sorption were obtained in NaClO 4 medium, and the europium(III) sorption edges were realized in KNO 3 medium to evaluate the influence of the complexing nitrate ions. Influence of the temperature, the nature of the cation and the nature of the substrate were pointed out by comparing the edges for the different systems. A structural investigation (TRLFS) was carried out to define experimentally, at the microscopic level, the sorption equilibria. Only UO 2 2+ and Eu 3+ were sorbed on both ZrP 2 O 7 surface sites (≡Zr–O and ≡P–O), the nitrate medium having no influence on the sorbed species. Furthermore, temperature did not change the sorption mechanisms. The surface complexation modelling of both investigated systems was realized using i) the constant capacitance model ii) the results of the substrate characterizations iii) uranyl sorbed complex determinations. The formation of bidentate surface complexes onto the ≡Zr–O site is not accompanied by a proton release, whereas the formation of bidentate surface complexes onto the ≡P–O site is followed by a release of 2 protons, for both cations and at all temperatures studied. The determined sorption constants increase with temperature, as was expected from the analysis of the sorption edge positions.

Multiwall carbon nanotubes (MWCNTs) have been pretreated with HNO 3 and used for the adsorption of radionuclide 152+154 Eu(III) from aqueous solutions. The effects of pH (2–12), ionic strength (0.01 M and 0.1 M NaClO 4 ) and radionuclide 152+154 Eu(III) solution concentrations (10 -8 –10 -5  mol/L) on the adsorption of 152+154 Eu(III) on MWCNTs were investigated. The experiments were carried out at 25±2 °C and under atmosphere conditions. Adsorption of 152+154 Eu(III) on MWCNTs increases significantly with increasing pH at pH <6, and over 96% 152+154 Eu(III) are adsorbed on MWCNTs at pH >6. Strong surface complexation and/or chemisorptions are considered as the main adsorption mechanism. The sorption was also characterized by using high resolution XPS spectra. The results show that MWCNTs can be a promising candidate of adsorbent for preconcentration of lanthanides from large volumes in radioactive nuclear waste management.

High-concentration samples of carrier-free 10 Be (up to 1 μg 10 Be per gram graphite) were separated from proton-irradiated graphite targets used at the meson production unit of the Paul Scherrer Institute (PSI). 10 Be concentrations were determined both with accelerator mass spectrometry (AMS) and inductively coupled plasma mass spectrometry (ICP-MS). The analytical results from both methods are in good agreement. The highly enriched 10 Be-samples will be used in scientific experiments relating to basic nuclear research and nuclear astrophysics in the framework of an international collaboration aimed to exploit accelerator waste material for scientific applications.

A simple, efficient and economical liquid–liquid extraction method has been developed for quantitative extraction of uranium from 2 M HNO 3 using di- n -butyl sulfoxide in petroleum ether. The dependence of the partition reaction of U(VI) on the concentration of HNO 3 , extractant and temperature was studied. The reaction was found to be inversely dependent upon the temperature and the values for related thermodynamics functions (Δ H , Δ S , Δ G ) for extraction equilibrium were determined to be -33.6 kJ/mol, -1.29 kJ/mol/degree and -0.11 kJ/mol/degree, respectively. The effect of Al(NO 3 ) 3 as salting-out agent and diverse ions on the extraction was examined. The salting-out agent slightly enhanced the extraction. All cations studied have showed negligible effect on the extraction, whereas phosphate and fluoride interfered seriously. Among others, oxalate, citrate and sulphide ions affect the extraction to a lesser extent. Uranium was successfully extracted from a synthetic mixture of Ti +4 , Zr +4 , Hf +4 and Th +4 using EDTA as masking agent. Among strippants, deionized water was found most suitable, and the recovery of uranium was noted to be ≥96%. The stoichiometric composition of the extracted species was found to be UO 2 (NO 3 ) 2 ·2DBSO. The extraction mechanism is discussed on the basis of the results obtained. The extractant has high loading as well as recycling capacity without any degradation. The method was also applied to the Standard Reference Material (NBL-49) and the measured value was found to be in agreement with the reported value within ±2% deviation.

Extractions of niobium and tantalum as homologues of dubnium (element 105) into tri-octylamine (TOA) in toluene from H 2 SO 4 and H 2 SO 4 /K 2 SO 4 solutions were performed to explore the possibilities of applying the automated on-line liquid–liquid extraction system SISAK to study chemical properties of dubnium in solutions. The results show that the extraction systems TOA/H 2 SO 4 and TOA/H 2 SO 4 +K 2 SO 4 are promising with respect to performing a study of Db with the SISAK system. Suggestions for performing a SISAK Db-experiment are presented. In batch experiments, Pa has also been investigated.

The speciation study of Cr(III) and Cr(VI) was carried out using a polyethylene glycol (PEG) based aqueous biphasic extraction system (ABS). Neutron activated Cr(III) and Cr(VI) salts were assayed in a HPGe detector before and after employing aqueous biphasic extraction. Different salts of various salting out abilities were taken as the salt rich phase. The best condition for extraction of Cr(VI) and the maximum differential attitude of ABS to Cr(VI) and Cr(III) was observed when 2 M Na 2 SO 4 and PEG #4000 (50% w/w) solutions were used. Cr(III) can also be extracted by the PEG with prior complexation with diphenylthiocarbazone (dithizone). The chromium dithizonate complex is quantitatively extracted by the PEG rich phase.

The suitable nuclear decay characteristics [ T 1/2 =6.73 d, E β (max) =497 keV, E γ =113 keV (6.4%), 208 keV (11%)] as well as the feasibility of large-scale production with adequate specific activity and radionuclidic purity using a moderate flux reactor are important attributes towards 177 Lu to be considered as a promising radionuclide for palliative care in painful bone metastasis. The present study describes the preparation of 177 Lu complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene phosphonic acid (DOTMP) and its preliminary biological evaluation in animal models with an aim to proposing it as a viable radiopharmaceutical for bone pain palliation. The choice DOTMP as the polyaminophosphonic acid carrier ligand is based on the enhanced thermodynamic stability and kinetic inertness of the metal-ligand complexes with macrocyclic chelators. 177 Lu was produced with a specific activity of ∼12 GBq/mg (∼324 mCi/mg) and radionuclidic purity of 99.98% by irradiation of natural Lu 2 O 3 target at a thermal neutron flux of ∼6×10 13  n/cm 2 s for 21 d. 177 Lu-DOTMP complex was prepared in high yield and excellent radiochemical purity (>99%) using DOTMP synthesized and characterized in-house. The complex exhibited excellent in-vitro stability at room temperature. Biodistribution studies in Wistar rats showed rapid skeletal accumulation of the injected activity [(1.60±0.19) per gram in femur at 3 h post-injection] with fast clearance from blood and minimal uptake in any of the major organs. Scintigraphic studies carried out in normal Wistar rats and New Zealand white rabbits also demonstrated significant accumulation of the agent in skeleton and almost no retention in any other vital organs.

Instrumental neutron activation analysis (INAA) was applied for multi-element determination in samples of graphite used in manufacturing of pencils. These samples have been randomly selected from the Egyptian market from different manufacturers and of various origins. Some of these samples are imported from the world market and the others are locally made. The determined elements in these samples were: As, Au, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Lu, Na, Ni, Rb, Sc, Ta, Th, U, W, Yb and Zn. Some of these elements were major or minor elements where others were trace elements. Standard reference material was used in this analysis. Some of the analyzed samples contain some toxic or undesirable elements such as As, Th and U. In addition some of these elements are present in comparatively high concentration.