Stratégies analytiques pour l'extraction séquencée du Th, U, Ra, Pb et Po dans des matrices environnementales

Authors: Dalencourt, Claire
Advisor: Larivière, Dominic
Abstract: Natural radioactivity is ubiquitous and reported in industrial wastes, such as mining residues. Its presence raises the issue of the management and the sustainability of such wastes. The content in radioactive elements allows to establish the radioactive potential of the residues, necessary to demonstrate their safety for an eventual revalorization. The quantification of the main elements of the thorium and uranium decay series, mainly responsible of natural radioactivity, allows to predict the radioactive potential. In the case of mining residues, current methodologies are not always reliable due to analytical uncertainties, often flirting with governmental limitations. To overcome this issue, new methods must be developed to handle complex matrices as well as being fast, precise and robust. The aim of this thesis is to develop a unique innovative method that combine several sequential resins to selectively extract thorium, uranium, radium, lead and polonium. The targeted analyte can be recovered after selective elution on a single resin. The segregation of the elements from interfering elements originating from the matrix allows their precise measurement on instruments such as alpha spectrometry or inductively coupled plasma mass spectrometry. To ensure the reliability of the analysis, total sample dissolution techniques have also been investigated. This thesis brings a valuable complement to current techniques such as gamma spectrometry, to screen natural radioactivity with accuracy and precision. Thus, the proposed technique could be applied in both industrial support laboratories and research laboratories. To guide the reader, a theorical part dealing with the chemical and physical properties of elements of interest will be provided. In addition, standard methodologies on their quantification will also be detailed in order demonstrate the novelty of the work presented in this thesis.
Document Type: Thèse de doctorat
Issue Date: 2019
Open Access Date: 15 October 2019
Grantor: Université Laval
Collection:Thèses et mémoires

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