Volume 106, Issue 6

In carbonate-buffer seawater or salt lake brines, three main uranium complexes, U(VI)-CO 3 and Ca/Mg-U(VI)-CO 3 complexes had been highlighted so far. In this paper, the effects of carbonate and its complexes on U(VI) adsorption onto doped polyaniline (PANI) were investigated using batch adsorption experiments. The adsorption equilibrium of U(VI) on doped PANI was reached within 30 min of contact time when U(VI)-CO 3 complexes dominated the aqueous chemistry. Pseudo-second order and Langmuir isotherm models indicated that adsorption occurred on the homogeneous surface via monolayer chemisorption. Moreover, the increase in pH initial , dissolved carbonate, calcium and magnesium concentrations could suppress the uranium adsorption process. The adsorption mechanisms under the weakly basic conditions were primarily involved in uranium anion species adsorption on nitrogen-containing functional groups instead of the anion exchange reactive sites on the doped PANI surface sites, whereas the U(VI)-CO 3 complexes had a greater affinity than the Ca/Mg-U(VI)-CO 3 complexes. The findings of this study are significant for the extraction of uranium resources from salt lake brines or seawater and for the prediction of uranium adsorption behaviors in weakly basic solution environments.

Laser induced breakdown spectroscopy recently has been investigated for analysis of nuclear waste glass for uranium quantification. The initial obtained accuracy and precision was ~15%. In this paper, we have compared the analytical merit of the univariative and multivariative PLSR regression models for the determination of U in barium borosilicate simulated waste glass containing significant amount of U. The analytical merit of a Czerny-Turner spectrograph with high spectral resolution and Echelle spectrograph with broadband spectrum recording capacity were compared using spectra simultaneously record from the same plasma. For univariative calibration the superiority of Czerny-Turner spectrograph over the Echelle has been demonstrated here. Multivariative chemometric PLSR model was found to drastically improve the results. It was also observed that selection of spectral window for analysis significantly affects the analytical merit of multivariative analysis. Echelle though shows relatively inferior analytical merit, but by applying Analytical spectral dependant PLSR in Echelle spectra, a much higher degree of improvement was observed. Using ASD-PLSR and Czerny-Turner spectrograph generated spectra an accuracy and precision of 2–2.5% was achieved in this study.

The present study evaluates the performance of ion flotation process for removal of uranyl tricarbonate complex, UO 2 (CO 3 ) 3 4− , which is the dominant species in many aqueous media particularly seawater, from aqueous solutions using cetyltrimethylammonium bromide, CTAB, as a cationic surfactant. Flotation of UO 2 (CO 3 ) 3 4− as a function in the solution pH is investigated in absence and in presence of carbonate. Removal percentage >99% is achieved in the pH range 8.5–11.5 in presence of 5×10 −3 M carbonate. The influence of concentrations of ethanol (0.1–2% v/v) and CTAB (5×10 −5 –1.4×10 −3 M) show that UO 2 (CO 3 ) 3 4− is efficiently removed at concentrations of 0.5–1.5% v/v and 4×10 −4 –1×10 −3 M, respectively. Based on the obtained kinetic data, the flotation mechanism and the flotation rate are investigated using two different flotation models. Floatability of UO 2 (CO 3 ) 3 4− in presence of different cations (Ba 2+ , Ca 2+ , Mg 2+ and Sr 2+ ) and anions (NO 3 − , Br − , Cl − , SO 4 2− and HPO 4 2− ) is studied. Except for Mg 2+ and NO 3 − , the flotation efficiency of UO 2 (CO 3 ) 3 4− is significantly decreased at concentrations higher than 1×10 −3 and 5×10 −3 M of the studied cations and anions, respectively. Ion flotation process is efficiently applied for removal of uranium(VI), R%>98.5%, from seawater. Accordingly, ion flotation can be considered as a promising technique and thus its feasibility for removal and/or recovery of uranium(VI) from many aqueous environment.

Molecular dynamics (MD) simulations were carried out to obtain molecular level insights on the behavior of Cs + /Na + ions at the water–ionic liquid and water–octanol interface in the presence of dibenzo-18-crown-6 (DB18C6) ionophore with an aim to compare an ionic liquid (IL) to a octanol as receiving organic solvent phase. It was observed that the rate of phase separation for the octanol system was rapid as compared to the IL system. The free crown ethers (CE) were found to be highly solvated by the IL phase. A dual cationic exchange mechanism was observed at the [BMIM]/water interface. The [BMIM] + cation was found to exchange with both the metal ions in aqueous phase as well as with the metal ion aided by the ionophore. The self-diffusion coefficient of the 1:2 complex (0.07×10 −9 m 2 /s) at the octanol/water interface were found to be smaller than that of 1:1 complex (0.37 and 0.14×10 −9 m 2 /s). It was observed that the surface tension of ILs decreased in the presence of complexes and free CE, whereas the surface tension of water was found to increase in presence of salts (Cs + NO 3 − and Na + NO 3 − ). The experimentally determined value of D Cs was found to be quite high in IL phase (1.595) compared to the octanol phase (0.139) in presence of CE. The kinetics of Cs + was found to be very fast having rate with values of k1^$\widehat {{k_1}}$=1.79×10 −12 s −1 and k2^$\widehat {{k_2}}$=0.205×10 −12 s −1 in IL and water phase, respectively. The present results may help us in understanding the role of diluents in the assisted metal ion extraction but also in the future design of diluents and ionophore.

A fast and efficient process for the production of the PET radionuclide 73 Se was developed using 75 Se as a surrogate. 75 Se was separated from proton irradiated arsenic trioxide by reaction with 2,3-diaminonaphthalene to 4,5-[ 75 Se]benzopiazelenol. This compound was purified using SPE column chromatography and subsequently decomposed with hydrogen peroxide. For further chemical conversions [ 75 Se]selenite was reduced to elemental [ 75 Se]selenium by either using thiosulfate or sulfur dioxide. The recovery yield of 75 Se from the target amounted to 43%. The utility of the isolated 75 Se for radiosyntheses was demonstrated by the successful preparation of [ 75 Se]selenomethionine. The methodology developed using 75 Se was successfully transformed to 73 Se.

177 Lu-PSMA-617 therapeutic agent was prepared successfully under optimized condition of pH=4.5, molar ratio of metal to ligand 1:10, temperature of 95°C and 40 min reaction time. 177 LuCl 3 was obtained with specific activity of 70–80 GBq/mg by the thermal neutron irradiation (5×10 13 n cm −2 s −1 ) of the enriched Lu 2 O 3 (52% 176 Lu) samples. The radionuclidic purity of 177 LuCl 3 (>99%) was checked by a HPGe detector. The radiochemical purities of 177 LuCl 3 solution and 177 Lu-PSMA-617 compound (>98%) were checked by ITLC and HPLC techniques and stability studies were assayed in the presence of human serum. Biodistribution and imaging assessments in the breast adenocarcinoma-bearing mice showed a major accumulation of activity in the tumor and kidneys tissues, as the expression site of PSMA molecule and the main route of excretion, respectively.

To study the compositional trends of rare earth elements (REEs: La, Ce, Nd, Sm, Eu, Tb, Dy, Yb, Lu), Th and U in soil samples collected from a site for a potential coal based power plant as well as to conduct a preliminary assessment of environmental impact of the proposed power plant in terms of REEs, Th and U, we have analyzed nine soil samples by instrumental neutron activation analysis. Evaluation of data quality by repeated analysis of IAEA-Soil-7 and IAEA-SL-1 ensures a proper data base-line for the REEs, Th and U abundances of the sampling site. Chondrite-normalized abundance patterns demonstrate the heavy REEs–light rare earth elements and Th–U fractionations in our sample suite along with significant negative Eu anomaly. Thorium/U ratio in our study area ranges from 4.55 to 6.07 which is higher than that of upper continental crust. Preliminary assessment of environmental impact of the proposed power plant is evaluated by taking NIST-SRM-1633b (coal-fly-ash) as contaminant as coal-fly-ash will be the major byproduct of the power plant. Previous literature studies and our prevailing data invoke that proposed power plant will have no severe impact on soil originated biota and on human health in terms of REEs, Th and U abundances. However, the long term effect of excessive REEs, Th and U as well as the other elemental abundances originating from coal-fly-ash should also be taken into an account.

The Algerian neutron activation analysis laboratory is highly involved in nutrition applications in the framework of research activities using the Es-Salam research reactor. The main objective of this work is to contribute, by using nuclear analytical techniques, for studying a large number of natural food samples consumed in Algeria related to nutrition and human health. The present study focuses on the analysis of the most popular beans consumed worldwide, namely, the coffee species of Arabica and Robusta, based on the international markets. Chemical content of samples was assessed by instrumental neutron activation analysis (INAA) and k 0 -INAA techniques, through the irradiation of samples during 6 h at a thermal neutron flux of 4.5×10 13 cm −2 s −1 of Es-Salam research reactor. A total of 17 elements were assessed such as, (Br, Ca, Ce, Co, Cr, Cs, Fe, K, La, Na, Rb, Sc, Sm, Sr, Zn, Lu and Th) obtained by using INAA and k 0 -INAA methods, While we used the radiochemical neutron activation analysis (RNAA and k 0 -RNAA) to determine Selenium at low level concentrations, the accuracy of the method was evaluated by analyzing CRM and SRM. QC/QA was evaluated by using the statistical parameter U-score. Results were compared with those obtained for samples from Brazilian, Caribbean, Indian and Kenyan coffee beans reported in the literature. The daily intake of essentials and toxic elements was determined and compared with the recommended values. The probable cumulative intake of toxic elements was found to be well below the tolerance limits.