Tesis doctoral de Elisenda ColÁ s Anguita
Radioactive wastes arise from almost all activities (nuclear and non-nuclear industry, research, military activities, medical applications) involving the handling of radioactive materials. There exists a clear necessity to dispose those wastes in order to avoid the radionuclides contained in the wastes being released to the biosphere in concentrations that could represent an unacceptable hazard to humans or to the environment. some of the materials present among radioactive wastes are made of organic polymers; other organic substances (e.G. Organic chemicals used in construction, buffer, and sealing materials) can also be present. Those organic substances may influence the behaviour of the radionuclides contained in the wastes. It is then necessary to assess the reactions that are likely to occur between radionuclides and those complexing agents, in order to estimate the quantities of radionuclides that can be transported out of the confinement. In order to do that, it is essential to know the relative stabilities of the compounds and complexes that may form under the relevant conditions, an information that is often provided by speciation calculations using chemical thermodynamic data. the main goal of this phd thesis is to obtain thermodynamic data that can be used to quantitatively predict the reactions between some organic ligands that may be present in a repository and radionuclides. Gluconate, isosaccharinate and edta have been studied, because they represent three different types of organic substances (cement additives, cellulose degradation products and decontamination agents) relevant for nuclear wastes. The experimental work has been conducted using natural th(iv) and natural u(vi). The attention has been focused mainly on the alkaline ph range, taking into account the key role of cement in conditioning matrices, engineered barriers and construction materials of waste repositories. two different type of experiments have been used to fulfil this objective: macroscopic solubility experiments and spectroscopic analyses the results obtained have allowed to: – obtain thermodynamic data (stability constants) in the thorium-gluconate system; – obtain experimental data in the thorium-isosaccharinate system. Taking into account the similarities between the chemical structure of gluconate and isosaccharinate, the analogy between both ligands has also been investigated; – increase the knowledge regarding the role of calcium in the thorium-gluconate and thorium-edta systems under the alkaline range; and – obtain data in the u(vi)-gluconate and u(vi)-edta systems.
Datos académicos de la tesis doctoral «Complexation of th(iv) and u(vi) by polyhydroxy and polyamino carboxylic acids«
- Título de la tesis: Complexation of th(iv) and u(vi) by polyhydroxy and polyamino carboxylic acids
- Autor: Elisenda ColÁ s Anguita
- Universidad: Politécnica de catalunya
- Fecha de lectura de la tesis: 05/05/2014
Dirección y tribunal
- Director de la tesis
- Mireia Grive Sole
- Tribunal
- Presidente del tribunal: Jorge Bruno salgot
- Javier Gaona martínez (vocal)
- bernd Grambow (vocal)
- eric Giffaut (vocal)