Publications

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    ABSTRACT: As part of an ongoing effort to develop new radionuclides inorganic adsorbents with interesting characteristics for spent nuclear fuel reprocessing and disposal activities we studied four monodisperse colloidal core@shell and @shell materials designed around a silica core and a zirconia shell. The removal capacity and kinetic behaviour of uranium as well as the effect of aged materials on the extraction ability of U were investigated. We found that all materials tested were able to extract reasonably high amounts of U and reached a kinetic equilibrium in aproximately10 min. The extraction capacity was maintained in a low acidity media except for the crystalline core@shell samples which exhibited a decrease of 60 % in its extraction ability. Americium, plutonium, protactinium and polonium extractions showed diverse behaviour depending on the element and aqueous media conditions. Finally, the particles stability in aqueous media was studied through the analysis of silicon and zirconium presence in solution after 48 h. Our results indicated that the materials possess a reasonably high stability.
    XII Jornadas Argentinas de Tratamiento de Minerales (XII JATRAMI), San Luis, Argentina; 10/2014
  • Charles Labrecque, Dominic Larivière
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    ABSTRACT: This article describes the development of a procedure for the bulk separation and determination of rare earth elements in soils by combining alkaline fusion, cloud point extraction, and inorganic mass spectrometry. The proposed cloud point extraction method uses a diglycolamide derivative as the chelating agent, which has a well-established affinity for rare earth elements. The method integrates bromine shielding to achieve efficient phase separation at highly acidic pH values. The methodology led to very low detection limits (0.2 to 30 ng/L), quantitative extraction (>97%) for soils, and a high preconcentration factor (up to 140). Decontamination factors were assessed for the most abundant elements, including trivalent ions such as Al3+ and Fe3+. A reduction in concentration of up to 180-fold was measured for some elements. Quantitative recoveries for most rare earth elements in highly acidic conditions were achieved and validated using sediment reference material (NIST-2709a). There was excellent agreement between the expected and measured concentrations for all 16 rare earth elements evaluated. The superior analytical figures of merit enabled rare earth element determination at ultra-trace levels in environmental samples.
    Analytical methods 10/2014; · 1.86 Impact Factor
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    Pablo J Lebed, Dominic Larivière, Xiongxin Dai
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    ABSTRACT: In this contribution we report our efforts to produce a protactinium standard through purification of Pa-231 from uranium ores in order to obtain measurable quantities. Through this process we explore the full range of the analytical process: from comparing sample preparation methods such as microwave digestion and fusion, the characterization of protactinium retention in commercial solid phase extraction resins with breakthrough curves and the challenges of detection and measurement with alpha spectrometry and ICP-MS.
    97th Canadian Chemical Conference and Exhibition, Vancouver, Canada; 06/2014
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    ABSTRACT: Analyse des bouteilles de la collection du Musée maritime du Québec.
    XXXIII Colloque Annuel de l`Association des archéologues du Québec, Trois-Rivières, Canada; 05/2014
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    ABSTRACT: An analytical procedure for determining the relative amounts of 60 Co and its 60 Ni daughter in a radioactive cobalt source by means of chromatographic separation and radiometric and mass spectrometric detection was developed, optimized and assessed through two round robin exercises for nuclear forensic investigations. Solid phase extraction (EXC) using Ni resin (Eichrom) and ion exchange (IEC) using Dowex-1X8 (Acros Organics) chromatographic approaches were considered for separating Co and Ni. Decontamination factors of 25 and 2.8 Â 10 6 were measured for EXC and IEC, respectively. Based on those results, only the IEC option was pursued. The effects of particle size, mass of resin, and degree of cross-linkage for decontamination performance were assessed, and the loading/eluting conditions were optimized. Canadian (CNSC, RPB, UL, RMC, AECL) and American (ANL) laboratories participated in two round robin exercises designed by the National Research Council of Canada to determine the suitability and limitations of the proposed methods. Age determination for freshly irradiated sources (<1 a) and for sources with high Ni content was challenging for the laboratories. Nevertheless, age estimates were obtained with sufficient accuracy for nuclear forensic purposes.
    Analytical methods 02/2014; 6(4):983-992. · 1.86 Impact Factor
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    Pablo J Lebed, Sabrina Potvin, Dominic Larivière, Xiongxin Dai
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    ABSTRACT: Effective solid phase extraction separation methods of actinides and fission products are required in the control and evaluation of common or experimental nuclear spent fuel reprocessing strategies and environmental contaminated samples. In this study, we have developed a simpler sequential analytical separation scheme to isolate 237Np from U and Pu. Experimental design tools were used to achieve parameter optimization. We studied the contribution of critical factors such as the type of resin, acidity, sulfamic acid concentration and sample volume to actinide extraction with a multivariate approach. Following a sequential assembly approach, fractional factorial designs were used to select the best resin. Full factorial designs were used to evaluate the expected response for the chosen multifactorial space. After discarding a first order linear model, the designs were augmented and the response surface methodology was used to evaluate the response through the use of a quadratic model together with graphical and canonical analysis. Knowledge acquired from multiple actinide responses allowed us to find multi-criteria compromise solutions that were successfully applied for the separation of Np from Pu and U in complex matrices.
    Analytical methods 01/2014; 6(1):139. · 1.86 Impact Factor
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    ABSTRACT: The importance of rare-earth elements (REEs) in the global economy is booming as they are used in numerous advanced technologies. Industrially, the extraction and purification of REEs involve multiple liquid–liquid extraction (LLE) steps as they exhibit very similar complexation properties with most common ligands. In order to substantially improve this process and provide a greener alternative to LLE, functional porous hybrid materials, demonstrating enhanced selectivity towards heavier REEs compared to commercially-available products, are proposed. In addition, because of the grafting procedure used in the synthesis, the proposed materials demonstrate a higher degree of reusability, increasing their marketable potential.
    Advanced Functional Materials 01/2014; · 10.44 Impact Factor
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    ABSTRACT: The importance of rare‐earth elements in the global economy is booming as they are used in numerous advanced technologies. However, industrially, their extraction and purification remain tedious. Functional nanoporous hybrid materials, represented by D. Larivière, F. Kleitz, and co‐workers as an asteroid preferentially cycling around a rare‐earth planet, demonstrate enhanced affinity for the rare‐earths with a high level of reusability, which increases their marketable potential. The image emphasizes the selectivity and reusability of these new extraction materials towards rare‐earths, rather than gravitating around actinide and other metal contaminants.
    Advanced Functional Materials 01/2014; 24(18). · 10.44 Impact Factor
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    ABSTRACT: Abstract Purpose: To assess the dosimetry of Ra-226 in a two year chronic ingestion study in laboratory maintained fathead minnow fed environmentally relevant levels of the isotope known to occur in gut contents of fish from a uranium mining area. Methods: Fish were established on reconstituted commercial fish food containing 10mBq-10Bq Ra-226.g(-1) dry food. The fish were sampled at 1,6,18 and 24 months and the Ra-226 levels in the whole fish were directly determined using measurement performed using inorganic mass spectrometry. Pilot experiments using higher doses were also done during development of a liquid scintillation detection system which support some data. Results: The data show that after 1 month the levels of accumulation in the fish were below detection. At 6 months there was an activity dependent accumulation which was relatively higher in the low activity groups. By 18 and 24 months the radium was very low in all groups - well below 6 month levels suggesting considerable loss of radium from the fish. These data were confirmed in a small and shorter study using higher dietary activities. The highest dose calculated for any measurement point was 16 μGy.h(-1) in the 6 month old fish fed the diet containing 10Bq.g(-1) Conclusions: We conclude that environmentally relevant levels of Ra-226 have a maximum impact at early time points when the fish are still growing. After that they appear to depurate accumulated radium. In terms of environmental impact the maximum accumulation peaks at the age where fish could be spawning but is extremely low leading to μGy.year(-1) doses even after exposure to the high activity diets.
    International Journal of Radiation Biology 11/2013; · 1.84 Impact Factor
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    ABSTRACT: Fluorescent CdSe-CdS-Cd0.5Zn0.5S-ZnS core-shell colloidal quantum dots (cQDs) dispersed in aqueous and organic solvents have been prepared and used as scintillators for detecting ionizing radiation. Results demonstrate a linear relationship between emitted luminescence and dose-activity. These results suggest that cQDs alone could be used as liquid scintillators for specific environmental and medical applications.
    Chemical Communications 11/2013; · 6.38 Impact Factor
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    ABSTRACT: A new cloud point extraction procedure has been developed for the quantification) of plutonium (IV) in environmental samples. The separation procedure can be either coupled to inductively coupled plasma mass spectrometry (ICP-MS) or alpha spectrometry for plutonium quantification. The method uses a combination of selective ligand (P,P di-(2-ethylhexyl) methanediphosphonic acid (H2DEH[MDP])) and micelle shielding by bromine formation to enable quantitative extraction of Pu in highly acidic solutions. Cross-optimization of all parameters (non-ionic and ionic surfactant, chelating agent, bromate, bromide and pH) led to optimal of the extraction conditions. Figures of merit of the method for the detection using alpha spectrometry and ICP-MS are reported (limit of detection, limit of quantification, minimal detectable activity and recovery). Quantitative extractions (> 95 %) were obtained for a wide variety of aqueous and digested samples (synthetic urine, waste water, drinking water, sea water and soil samples). The method features the first successful coupling between alpha spectrometry and cloud point extraction and was the first demonstration of CPE suitability with metaborate fusion as a sample preparation approach, all techniques used extensively in nuclear industries.
    Analytical Chemistry 09/2013; · 5.70 Impact Factor
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    Pablo J Lebed, Sabrina Potvin, Dominic Larivière, Xiongxin Dai
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    ABSTRACT: Ultra-trace analysis of radionuclides, particularly actinides and fission products, is required for a number of important applications including nuclear forensics and radio-bioassay. In the field of environmental radio-analytical chemistry current 237Np separation protocols are mainly based on the use of TEVA EXC commercial where samples are usually loaded after reduction of Np to Np(IV) while Pu is in the non-retainable Pu(III) oxidation state. Traditionally, these time consuming separation methodologies are developed by monitoring the influence of one-variable-at-a-time on an experimental response. Although it is possible to obtain successful results, this approach presents disadvantages such as the increase in the number of necessary experiments and the lack of inclusion of the interactive effects among the variables studied with the consequence of an incomplete effect description over the response. Multivariate statistic techniques have proven to be valid tools in the pathway of simultaneous parameters optimization to achieve the maximum system performance. The aim of the present work is to show that it is possible to develop a much simpler time-saving analytical separation scheme to obtain 237Np samples free from 238U and 242Pu through the application of experimental design tools, mainly fractional and full factorial designs, and the response surface methodology (RSM). Knowledge acquired from multiple actinide responses allowed us to find multi-criteria compromise solutions that were successfully applied over complex matrices such as waste water and soil.
    EnviroAnalysis 2013, Toronto, Canada; 09/2013
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    ABSTRACT: Abstract Purpose: To assess the impact of environmentally relevant levels of ingested (226)Ra on a common freshwater fish species. Methods: Fathead minnow (Pimephales promelas, Rafinesque) were obtained at the first feeding stage and established on a commercial fish food diet containing (226)Ra in the activity range 10mBq/g-10,000mBq/g. They remained on this diet for 24 months and were sampled invasively at 1,6,18 and 24 months to assess growth, biochemical indices and accumulated dose and non-invasively also at 12 and 15 months to assess growth. Results: Fish fed 10 and 100mBq/g diet showed a small transitory deregulation of growth at 6 and 12 months. Fish fed higher activities showed less significant or insignificant effects. There was a trend at 18 months which was stronger at 24 months for the population distribution to change in all of the (226)Ra fed groups so that smaller fish were smaller and bigger fish were bigger than the controls. There were also significant differences in the ratios of protein: DNA at 24 months which were seen as a trend but were not significant at earlier time points. Conclusions: Fish fed a radium diet for 2 years show a small and transitory growth dysregulation at 6 and 12 months. The effects predominate at the lower activities suggesting hormetic or homeostatic adjustments. There was no effect on growth of exposure to the high activities 226Ra. This suggests that Radium does not have a serious impact on the ecology of the system and the level of radium that would be transferred to humans is very low. The results may be important in the assessment of long-term environmental impacts of (226)Ra exposure.
    International Journal of Radiation Biology 06/2013; · 1.84 Impact Factor
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    ABSTRACT: A procedure has been developed for the cloud point extraction (CPE) of uranium (VI) using H2DEH[MDP] (P,P-di(2-ethylhexyl) methanediphosphonic acid) with inductively coupled plasma coupled to mass spectrometry (ICP-MS). The method is based on the modification of the cloud point temperature using cetyl trimethyl ammonium bromide (CTAB) and KI. Optimal conditions of extraction were found using a cross-optimization of every parameter (non-ionic and ionic surfactant concentrations, chelating agent concentration, pH and the extraction, and phase separation temperatures). Furthermore, the figures of merit of the methodology were assessed (limit of detection, limit of quantification, recovery, sensibility, and linear range) and are reported. Quantitative extraction (99±0.5%) was obtained in drinking water samples over a wide range of uranium concentrations. The approach was also validated using drinking (SCP EP-L-3 and SCP EP-H-3), and wastewater (SCP EU-L-3) certified materials. Interferences from most critical anions and cations were evaluated to determine the reliability of the method. The proposed method showed robustness since its performance is maintained over a wide range of pH and metal ion concentrations.
    Talanta 03/2013; 107C:284-291. · 3.50 Impact Factor
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    ABSTRACT: Cesium pre-concentration/separation was investigated using novel ammonium molybdophosphate (AMP)-based adsorbents supported on mesoporous silica (SBA-15). This combination is a viable strategy to produce reusable, highly effective and selective adsorbents to be used for remediation during radiological/nuclear events or radiological monitoring.
    New Journal of Chemistry 01/2013; 37:3877-3880. · 2.97 Impact Factor
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    ABSTRACT: Potential consequences of radiological/nuclear events on the population and the environment have led the scientific community to rethink its approach toward a monitoring based on radiochemical separation. In this context, there is a great need to design radioanalytical systems for quickly evaluating environmental impacts in case of incidents and nuclear events. Phosphonate-functionalized large pore three-dimensional (3-D) cubic (KIT-6) and two-dimensional (2-D) hexagonal (SBA-15) silicas have been studied as highly efficient uranium extracting adsorbents in acidic media. In both cases, functionalization was performed by grafting (2-diethylphosphatoethyl) triethoxysilane (DPTS) on the mesopore surface of the silica supports. Particular attention was given to comparison of different pore sizes and pore structures and impact on radionuclide extraction, principally through uranium adsorption isotherms and sorption kinetics studies. All hybrid materials demonstrated very fast adsorption kinetics, reaching equilibrium in less than 60 s. Calculated parameters from the Langmuir model revealed a clearly superior performance of the 3-D cubic KIT-6-based sorbents compared to other equivalents, especially for uranium equilibrium concentrations below 50 mg L–1. Furthermore, a superior maximum adsorption capacity in the range of 54–56 mg of U per gram of sorbent was observed for which it represents almost a 3-fold increase compared to the capacity of commercially available products. High extraction efficiency is demonstrated through dynamic extraction experiments using less than 25 mg of functionalized mesoporous resin analogue. Importantly, the possibility of reusing regenerated mesoporous sorbents is established over several cycles with no loss in uranium extraction capacity suggesting adequate chemical and structural stability of the new sorbent materials.
    Chemistry of Materials 10/2012; 24:4166−4176. · 8.24 Impact Factor
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    ABSTRACT: Uranium (U) is an ubiquitous radioelement found in drinking water and food. As a consequence of its prevalence, most humans ingest a few micrograms (μg) of this element daily. It is incorporated in various organs and tissues. Several studies have demonstrated that ingested U is deposited mainly in bones. Therefore, U skeletal content could be considered as a prime indicator for low-level chronic intake. In this study, 71 archived vertebrae bone samples collected in seven Canadian cities were subjected to digestion and U analysis by inductively coupled plasma mass spectrometry. These results were correlated with U concentrations in municipal drinking water supplies, with the data originating from historical studies performed by Health Canada. A strong relationship (r(2) = 0.97) was observed between the averaged U total skeletal content and averaged drinking water concentration, supporting the hypothesis that bones are indeed a good indicator of U intake. Using a PowerBASIC compiler to process an ICRP systemic model for U (ICRP, 1995a), U total skeletal content was estimated using two gastrointestinal tract absorption factors (ƒ(1) = 0.009 and 0.03). Comparisons between observed and modelled skeletal contents as a function of U intake from drinking water tend to demonstrate that neither of the ƒ(1) values can adequately estimate observed values. An ƒ(1)value of 0.009 provides a realistic estimate for intake resulting from food consumption only (6.72 μg) compared to experimental data (7.4 ± 0.8 μg), whereas an ƒ(1)value of 0.03 tends to better estimate U skeletal content at higher levels of U (1-10 μg L(-1)) in drinking water.
    Journal of Environmental Radioactivity 06/2012; · 3.67 Impact Factor
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    ABSTRACT: The Ministry of Sustainable Development, Environment and Parks of Québec (Ministère du Développement durable, de l'Environnement et des Parcs du Québec-MDDEP) held a 3-d provincial nuclear emergency response exercise in September 2008 that saw participation from Canadian provincial and federal departments. Nuclear emergency exercises are regularly held in Québec, given the presence of the Gentilly-2 nuclear power plant situated in Bécancour on the St. Lawrence River. The significance of this exercise is that it marks the first exercise held in Canada where environmental samples spiked with relevant radioisotopes were analyzed during the exercise, both on-site and remotely, and where the results of those analyses had a direct impact on the decisions made during the exercise. Following the exercise, samples were sent to two other laboratories that are part of the Canadian National Nuclear Laboratory Network for analysis, providing the first intercomparison exercise for the Network. The results of the analysis of the air and drinking water samples, as well as the lessons learned during the exercise, are presented and discussed in this article.
    Health physics 05/2012; 102(5 Suppl 2):S67-78. · 0.92 Impact Factor
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    ABSTRACT: Several techniques are commercially implemented to extract actinides. Among them, extraction chromatographic resins provide excellent selectivity for a wide range of actinides. However, their limitations are their instability during repeated washing, irradiation and recycling. Recently, the use of mesoporous materials (SBA-15, KIT-6 silicas) as supports for the extracting agent has led to improved extraction techniques. Compared to the resins, they have the advantage of maintaining their integrity upon extraction (solvent), higher yields and good compatibility for different analytes. The purpose of this work is to compare actinide extraction properties of KIT-6 (3-D pore structure) functionalized with phosphonates (KIT-6-P), with a commercial resin and SBA-15-P (2-D pore structure). Particular attention is placed on a comparison of the actinide adsorption isotherms and kinetics as a function of the different pores structures, as well as the potential for regeneration.
    CPM 6 - 6th International Workshop, Miami, USA; 04/2012

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