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  • Uranium speciation studies at alkaline pH and in the presence of hydrogen peroxide using time-resolved laser-induced fluorescence spectroscopy

     Martinez Torrents, Albert; Meca, Sandra; Baumann, Nils; Marti Gregorio, Vicenç; Gimenez Izquierdo, Francisco Javier; Pablo Ribas, Joan de; Casas Pons, Ignasi
    Polyhedron
    Vol. 55, p. 92-101
    DOI: 10.1016/j.poly.2013.02.075
    Date of publication: 2013-05
    Journal article

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    Time-resolved laser-induced fluorescence spectroscopy (TRLFS) was used to study the speciation of uranium(VI) at very alkaline pH (11-13), at room temperature and in the absence of CO2. In this case, at pH = 11, two different fluorescence lifetimes appeared, which were attributed to the species UO2(OH)(3)(-) and (UO2)(3)(OH)(7)(-). At pH = 13, no fluorescence was detected, indicating that the predominant species, UO2(OH)(4)(2-), is not fluorescent. At pH = 12, the lifetime obtained is attributed to the predominant species UO2(OH)(3). Because of the absence of fluorescence of the UO2(OH)(4)(2-) species at room temperature, measurements at 10 K were made, obtaining two different lifetimes in the pH range between 12 and 13.5, indicating the presence of two different species: UO2(OH)(3)(-) and UO2(OH)(4)(2-). The difference between the lifetimes allowed the calculation of the contribution of each species to the total fluorescence signal intensity. From the experiments carried out in the presence of hydrogen peroxide, it was observed that hydrogen peroxide produces a quenching effect to the fluorescence of the uranium species. At pH 12 the quenching is static, which points to the formation of a non-fluorescent complex between U(VI) and hydrogen peroxide. Using the Stern-Volmer equation for static quenching, the equilibrium formation constant of the first species, UO2O2(OH)(2)(2-), was calculated to be logK(0) = 28.7 +/- 0.4, which is similar to the one determined using UV-Visible spectrometry, 28.1 +/- 0.2 Meca et al. (2011) [42]. (C) 2013 Elsevier Ltd. All rights reserved.

    Time-resolved laser-induced fluorescence spectroscopy (TRLFS) was used to study the speciation of uranium(VI) at very alkaline pH (11–13), at room temperature and in the absence of CO2. In this case, at pH = 11, two different fluorescence lifetimes appeared, which were attributed to the species UO2(OH)3− and (UO2)3(OH)7−. At pH = 13, no fluorescence was detected, indicating that the predominant species, UO2(OH)42−, is not fluorescent. At pH = 12, the lifetime obtained is attributed to the predominant species UO2(OH)3−. Because of the absence of fluorescence of the UO2(OH)42− species at room temperature, measurements at 10 K were made, obtaining two different lifetimes in the pH range between 12 and 13.5, indicating the presence of two different species: UO2(OH)3− and UO2(OH)42−. The difference between the lifetimes allowed the calculation of the contribution of each species to the total fluorescence signal intensity. From the experiments carried out in the presence of hydrogen peroxide, it was observed that hydrogen peroxide produces a quenching effect to the fluorescence of the uranium species. At pH 12 the quenching is static, which points to the formation of a non-fluorescent complex between U(VI) and hydrogen peroxide. Using the Stern–Volmer equation for static quenching, the equilibrium formation constant of the first species, UO2O2(OH)22−, was calculated to be logK0 = 28.7 ± 0.4, which is similar to the one determined using UV–Visible spectrometry, 28.1 ± 0.2 Meca et al. (2011) [42].

  • Dynamic leaching studies of 48 MWd/kgU UO2 commercial spent nuclear fuel under oxic conditions

     Serrano Purroy, D.; Casas Pons, Ignasi; Gonzalez Robles, E.; Glatz, Jean Paul; Wegen, D.H.; Clarens Blanco, Frederic; Gimenez Izquierdo, Francisco Javier; Pablo Ribas, Joan de; Martínez Esparza, A.
    Journal of nuclear materials
    Vol. 434, num. 1-3, p. 451-460
    DOI: 10.1016/j.jnucmat.2011.03.020
    Date of publication: 2013-03
    Journal article

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    The leaching of a high-burn-up spent nuclear fuel (48 MWd/KgU) has been studied in a carbonate-containing solution and under oxic conditions using a Continuously Stirred Tank Flow-Through Reactor (CSTR). Two samples of the fuel, one prepared from the centre of the pellet (labelled CORE) and another one from the fuel pellet periphery, enriched with the so-called High Burn-Up Structure (HBS, labelled OUT) have been used. For uranium and actinides, the results showed that U, Np, Am and Cm gave very similar normalized dissolution rates, while Pu showed slower dissolution rates for both samples. In addition, dissolution rates were consistently two to four times lower for OUT sample compared to CORE sample. Considering the fission products release the main results are that Y, Tc, La and Nd dissolved very similar to uranium; while Cs, Sr, Mo and Rb have up to 10 times higher dissolution rates. Rh, Ru and Zr seemed to have lower dissolution rates than uranium. The lowest dissolution rates were found for OUT sample. Three different contributions were detected on uranium release, modelled and attributed to oxidation layer, fines and matrix release.

    The leaching of a high-burn-up spent nuclear fuel (48 MWd/KgU) has been studied in a carbonate-containing solution and under oxic conditions using a Continuously Stirred Tank Flow-Through Reactor (CSTR). Two samples of the fuel, one prepared from the centre of the pellet (labelled CORE) and another one from the fuel pellet periphery, enriched with the so-called High Burn-Up Structure (HBS, labelled OUT) have been used. For uranium and actinides, the results showed that U, Np, Am and Cm gave very similar normalized dissolution rates, while Pu showed slower dissolution rates for both samples. In addition, dissolution rates were consistently two to four times lower for OUT sample compared to CORE sample. Considering the fission products release the main results are that Y, Tc, La and Nd dissolved very similar to uranium; while Cs, Sr, Mo and Rb have up to 10 times higher dissolution rates. Rh, Ru and Zr seemed to have lower dissolution rates than uranium. The lowest dissolution rates were found for OUT sample. Three different contributions were detected on uranium release, modelled and attributed to oxidation layer, fines and matrix release.

  • Desarrollo de tecnología a escala piloto para depuración de aguas contaminadas con iones metálicos mediante residuos agroalimentario

     Casas Pons, Ignasi; Martínez Martínez, María R.; Miralles Esteban, Nuria; Yacoub Lopez, Cristina; Florido Pérez, Antonio
    Competitive project

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  • Instant release fraction and matrix release of high burn-up UO2 spent nuclear fuel: Effect of high burn-up structure and leaching solution composition

     Serrano Purroya, D.; Clarens Blanco, Frederic; Gonzalez Robles, E.; Glatz, Jean Paul; Wegen, D.H.; Pablo Ribas, Joan de; Casas Pons, Ignasi; Gimenez Izquierdo, Francisco Javier; Martínez Esparza, A.
    Journal of nuclear materials
    Vol. 427, num. 1-3, p. 249-258
    DOI: 10.1016/j.jnucmat.2012.04.036
    Date of publication: 2012-08
    Journal article

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    wo weak points in Performance Assessment (PA) exercises regarding the alteration of Spent Nuclear Fuel (SNF) are the contribution of the so-called Instant Release Fraction (IRF) and the effect of High Burn-Up Structure (HBS). This manuscript focuses on the effect of HBS in matrix (long term) and instant release of a Pressurised Water Reactor (PWR) SNF irradiated in a commercial reactor with a mean Burn-Up (BU) of 60 GWd/tU. In order to study the HBS contribution, two samples from different radial positions have been prepared. One from the centre of the SNF, labelled CORE, and one from the periphery, enriched with HBS and labelled OUT. Static leaching experiments have been carried out with two synthetic leaching solutions: bicarbonate (BIC) and Bentonitic Granitic Groundwater (BGW), and in all cases under oxidising conditions. IRF values have been calculated from the determined Fraction of Inventory in Aqueous Phase (FIAP). In all studied cases, some radionuclides (RN): Rb, Sr and Cs, have shown higher release rates than uranium, especially at the beginning of the experiment, and have been considered as IRF. Redox sensitive RN like Mo and Tc have been found to dissolve slightly faster than uranium and further studies might be needed to confirm if they can also be considered part of the IRF. Most of the remaining studied RN, mainly actinides and lanthanides, have been found to dissolve congruently with the uranium matrix. Finally, Zr, Ru and Rh presented lower release rates than the matrix. Higher matrix release has been determined for CORE than for OUT samples showing that the formation of HBS might have a protective effect against the oxidative corrosion of the SNF. On the contrary, no significant differences have been observed between the two studied leaching solutions (BIC and BGW).

  • Kinetics of hydrogen peroxide consumption in aqueous phase at different hydrogen partial pressures

     Gimenez Izquierdo, Francisco Javier; Casas Pons, Ignasi; Sureda Pastor, Rosa Maria; Pablo Ribas, Joan de
    Radiochimica acta
    Vol. 100, num. 7, p. 445-448
    DOI: 10.1524/ract.2012.1940
    Date of publication: 2012
    Journal article

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  • Uranium speciation in river sediments contaminated by phosphate ores

     Meca, S.; Gimenez Izquierdo, Francisco Javier; Casas Pons, Ignasi; Marti Gregorio, Vicenç; Pablo Ribas, Joan de
    Environmental chemistry letters
    Vol. 10, num. 1, p. 49-53
    DOI: 10.1007/s10311-011-0327-1
    Date of publication: 2012-03
    Journal article

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    Large amounts of phosphate ores with high concentrations of uranium were dumped by a phosphate plant into the Flix water reservoir in the Ebre River, Catalonia, NE Spain. These phosphate wastes have been mixed over the years with effluents from other industries as well as with the sediments of the river, resulting in a complex mixture of solid wastes and sediments. No investigations on uranium speciation in such sediments were made because of the complexity of the sediments composition as well as the relatively low uranium content. However, these studies are necessary in order to predict the release of the uranium to the river waters. Here, we studied uranium speciation in sediments from two sampling points of the Flix water reservoir and at depths from 5 to 113 cm. We used room temperature time-resolved laser fluorescence spectroscopy and a three-step sequential extraction procedure described by the Standards, Measurements, and Testing Programme of the European Union. We found that uranium was mainly present in the sediment samples as meta-autunite [Ca(UO2)2(PO4)2 10–12H2O], whose low solubility will result in a low release of uranium to the river waters. In addition, we found that some uranium was linked to sediments by forming surface complexes. We therefore made the first study of uranium speciation in the sediments of the Flix water reservoir.

  • Disolución Del Combustible Nuclear Gastado en un Almacenamiento Geológico Profundo. Efecto De Los Productos Radiolíticos Y De Formación De Fases Secundarias  Open access

     Sureda Pastor, Rosa Maria
    Department of Chemical Engineering, Universitat Politècnica de Catalunya
    Theses

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    La gestión adecuada de los residuos radiactivos de elevada actividad es uno de los desafíos más complejos en nuestra sociedad industrializada y que suscita gran polémica social. La cantidad de residuos radiactivos producidos ha aumentado considerablemente debido principalmente a la creciente utilización de las centrales nucleares en la generación de energía eléctrica. El almacenamiento en formaciones geológicas contacto, la concentración de radionucleido en disolución y el pH. Los resultados muestran que la formación de esta fase secundaria sobre la superficie del CNG podría representar uno de los principales procesos de retención de radionucleidos. Por otra parte, la estabilidad de estas fases minerales se verá directamente afectada por dos de los variables más críticas en el campo próximo de un AGP que son la radiación y la temperatura. Los efectos a nivel atómico de la radiación ionizante sobre la estructura de los silicatos de U(VI): soddyíta (UO2)2(SiO4)(H2O)2 y uranofana Ca(UO2)2(SiO3OH)2·5H2O, se han investigado utilizando la técnica de microscopía electrónica de transmisión (TEM), permitiendo la observación in situ de los procesos de amorfización/nanocristalización de estas fases. Los estudios térmicos llevados a cabo mediante termogravimetría (TG) y calorimetría diferencial de barrido (DSC) combinado con la caracterización por difracción de rayos X (XRD) han permitido evidenciar la importancia de los procesos de deshidratación en la integridad estructural de cada fase. Finalmente, se ha estudiado la cinética de la reacción entre el peróxido de hidrógeno y el hidrógeno a temperatura ambiente y en ausencia de productos catalíticos. El seguimiento de la reacción se ha realizado a partir de la disminución de la concentración de peróxido de hidrógeno en disolución con el tiempo, observándose un aumento en la velocidad de reacción a medida que la presión de hidrógeno aumenta. Estos resultados indican que el hidrógeno podría actuar como inhibidor de la disolución de la matriz de CNG consumiendo la principal especie responsable del proceso de alteración oxidativa. profundas (AGP) se presenta como la opción más viable y definitiva para estos residuos. Para garantizar la seguridad del repositorio es necesario desarrollar modelos que predigan el comportamiento del combustible nuclear gastado (CNG) a largo plazo, así como la liberación y migración de radionucleidos (RN) al medio ambiente. La alteración del CNG dependerá de una serie de procesos que tienen lugar una vez el agua subterránea entre en contacto con la superficie del combustible como son, la formación de productos radiolíticos, su efecto en la oxidación de la matriz de UO2 y posterior disolución, y por último la precipitación de fases secundarias. El estudio de estas fases como productos finales del proceso de disolución oxidativa de la matriz es de gran interés ya que pueden afectar a la movilización de actínidos y productos de fisión, y al comportamiento a largo plazo del propio combustible. A parte de estos procesos, también hay que considerar la corrosión anóxica de la cápsula de acero que generará una gran cantidad de hidrógeno que puede influir en la disolución del CNG. Con el objetivo de profundizar en algunos aspectos relacionados con los productos radiolíticos y fases secundarias en el entorno más cercano al residuo, el denominado campo próximo de un AGP, en esta tesis se han desarrollado una serie de estudios que se resumen a continuación. En la primera parte, se ha estudiado la influencia de los productos radiolíticos: hipoclorito, clorito y clorato en la velocidad de disolución del UO2 como análogo a la matriz de CNG. Las velocidades de disolución obtenidas en el caso del hipoclorito, siguiendo la misma metodología experimental, resultaron ser más elevadas que las velocidades obtenidas en presencia de los principales oxidantes, como el oxígeno o el peroxido de hidrógeno. Una segunda parte se ha centrado en aumentar el conocimiento de las fases secundarias de U(VI) más representativas del proceso de alteración oxidativa del CNG. Concretamente, se ha estudiado la adsorción de cesio y estroncio sobre el peroxido de uranilo, studtita (UO2O2 4H2O), en función de distintos parámetros como el tiempo de

    La gestió adequada dels residus radioactius d’elevada activitat és un dels desafiaments més complexos en la nostra societat industrialitzada i que suscita gran polèmica social. La quantitat de residus radioactius produïts ha augmentat considerablement degut principalment a la creixent utilització de les centrals nuclears en la generació d’energía eléctrica. L’ emmagatzematge en formacions geològiques profundes (MGP) es presenta com a opció més viable i definitiva per aquests residus. Per tal de garantir la seguretat del repositori es necessari desenvolupar models que prediguin el comportament del combustible nuclear gastat (CNG) a llarg termini, així com l’alliberament i migració de radionúclids (RN) al medi ambient. L’alteració del CNG dependrà d’una sèrie de processos que tenen lloc un cop l’aigua subterrània entri en contacte amb la superfície del combustible como son, la formació de productes radiolítics, el seu efecte en l’oxidació de la matriu de UO2 i posterior dissolució, i por últim la precipitació de fases secundàries. L’estudi d’aquestes fases com a productes finals del procés de dissolució oxidativa de la matriu es de gran interès ja que poden afectar a la mobilització d’actínids i productes de fissió, i al comportament a llarg termini del propi combustible. A part d’aquests processos també s’ha de considerar la corrosió anòxica de la càpsula d’acer, la qual generarà una gran quantitat d’hidrogen que pot influir en la dissolució del CNG. Amb l’objectiu de profunditzar en alguns aspectes relacionats amb els productes radiolítics i fases secundàries en l’entorn més proper al residu, l’anomenat camp pròxim d’un MGP , en aquesta tesis s’han desenvolupat una sèrie d’estudis que es resumeixen a continuació. En la primera part, s’ha estudiat la influencia dels productes radiolíticos: hipoclorit, clorit i clorat en la velocitat de dissolució del UO2 como anàleg a la matriu de CNG. Les velocitats de dissolució obtingudes en el cas del hipoclorit, seguint la mateixa metodologia experimental, varen resultar ser més elevades que les velocitats obtingudes en presencia dels principals oxidants, como l’oxigen o el peròxid de hidrogen. Una segona part s’ha centrat en augmentar el coneixement de fases secundàries de U(VI) més representatives del procés d’alteració oxidativa del CNG. Concretament, s’han estudiat l’adsorció de cesi i estronci sobre el peròxid d’uranil, studtita (UO2O2 4H2O), en funció de diferents paràmetres com son el temps de contacte, la concentració de radionúclid en dissolució i el pH. Els resultats mostren que la formació d’aquesta fase sobre la superfície del CNG podria representar un dels principals processos de retenció de radionúclids. Per altre banda, l’estabilitat d’aquestes fases minerals es veurà directament afectada per dues de les variables més crítiques en el camp pròxim d’un (MGP) que son la radiació i la temperatura. Els efectes a nivell atòmic de la radiació ionitzant sobre l’estructura dels silicats de U(VI): soddyíta (UO2)2(SiO4)(H2O)2 i uranofana Ca(UO2)2(SiO3OH)2·5H2O, s’han investigat utilitzant la tècnica de microscopía electrònica de transmissió (TEM), que permet l’observació in situ dels processos d’amorfització/nanocristalizació d’aquestes fases. Els estudis tèrmics s’han realitzat mitjançant les tècniques de termogravimetria (TG) i calorimetria diferencial d’escombrat (DSC) combinat amb la caracterització per difracció de raigs X (XRD) que han permès evidenciar la importància dels processos de deshidratació en la integritat estructural de cada fase. Finalment, s’ha estudiat la cinètica de la reacció entre el peròxid de hidrogen i el hidrogen a temperatura ambient i en absència de productes catalítics. El seguiment de la reacció s’ha realitzat a partir de la disminució de la concentració de peròxid de hidrogen en dissolució amb el temps. S’ha observat un augment en la velocitat de reacció a mesura que la pressió de hidrogen augmenta. Aquests resultats indiquen que el hidrogen podria actuar com a inhibidor de la dissolució de la matriu de CNG consumint la principal espècie responsable del procés d’alteració oxidativa.

    Adequate management of High-activity radioactive waste is one of the most complex challenges in our industrialized society, which generates a lot of social controversy surrounding this issue. The amount of radioactive waste produced has increased considerably due, mainly, to the increased use of nuclear energy in generating electricity. Storage in deep geological formations is presented as the most viable option for a final disposal of these wastes. To ensure the safety of the repository it is necessary to develop models that predict the behavior of spent nuclear fuel (SNF) in the long-term storage, as well as the release and migration of radionuclides to the environment. The alteration of SNF under expected representative repository conditions will depend on a number of processes that take place once the groundwater come in contact with the surface of the fuel, such as the formation of radiolitic products, its effect on the matrix oxidation and subsequent dissolution, released of radionuclides contained in the fuel matrix and finally, precipitation of secondary phases. The study of these phases as end products of the oxidative dissolution process is of major interest due to the fact that they may affect the mobilization of actinides and fission products by geochemical processes such as adsorption. A part of these processes, we must also consider the anoxic corrosion of the steel capsule that will generate a large amount of hydrogen which can influence in the dissolution of SNF. In order to get deeper into some aspects of radiolytic products and secondary phases in the near-field of a High-level Nuclear Waste (HLNW) repository, in this thesis we have developed a series of studies which are summarized below. In the first part, the influence of hypochlorite, chlorite and chlorate in the dissolution rate of UO2 as a chemical analogue of the spent fuel matrix, has been studied experimentally. The dissolution rates obtained in this work are found to be higher than the rates determined in the presence of either oxygen or hydrogen peroxide obtained with same experimental methodology. A second part is focused on increasing the knowledge of the most representative secondary phases of U(VI) formed during the oxidative alteration of SNF. Specifically, the adsorption of cesium and strontium onto uranyl peroxide, studtite (UO2O2 4H2O), has been studied as a function of time, radionuclide concentration in solution and pH. The results show that this secondary solid phase formation on the SNF surface could be an important mechanism involved in the retention of radionuclides. On the other hand, the stability of these mineral phases will be directly affected by two of the most critical variables in the near-field of HLNW are radiation and temperature. Atomic-level effects of ionizing radiation on the structure of U(VI) silicates: soddyite (UO2)2(SiO4)(H2O)2 and uranophana Ca(UO2)2(SiO3OH)2·5H2O have been investigated using electron beam irradiation in a transmission electron microscope (TEM), which allows in situ observation of amorphization/nanocristallization processes of these phases. Thermal studies carried out by thermogravimetry (TG) and differential scanning calorimetry (DSC) combined with X-ray diffraction (DRX) have demostrated the importance of dehydration processes in the structural integrity for each phase. Finally, the reaction between aqueous hydrogen peroxide solutions and hydrogen has been studied at room temperature and in the absence of catalytic products. The reaction evolution has been determined by the decrease of hydrogen peroxide concentration with time. A clear effect has been observed, and the rate of reaction is found to be enhanced as the hydrogen pressure is increased. These results indicate that hydrogen could act as an inhibitor of spent fuel matrix dissolution through the consumption of the main species responsible for the oxidative alteration process.

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    Determination of the equilibrium formation constants of two U(VI)-peroxide complexes at alkaline pH  Open access

     Meca, S.; Martinez Torrents, Albert; Marti Gregorio, Vicenç; Gimenez Izquierdo, Francisco Javier; Casas Pons, Ignasi; Pablo Ribas, Joan de
    Dalton transactions
    Vol. 40, num. 31, p. 7976-7982
    DOI: 10.1039/c0dt01672a
    Date of publication: 2011
    Journal article

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    The formation of uranyl-peroxide complexes was studied at alkaline media by using UV-Visible spectrophotometry and the STAR code. Two different complexes were found at a H2O2/U(VI) ratio lower than 2. A graphical method was used in order to obtain the formation constants of such complexes and the STAR program was used to refine the formation constants values because of its capacity to treat multiwavelength absorbance data and refining equilibrium constants. The values obtained for the two complexes identified [...] At hydrogen peroxide concentrations higher than 10-5 mol dm-3, and in the absence of carbonate, the UO2(O2)2(OH)2 4- complex is predominant in solution, indicating the significant peroxide affinity of peroxide ions for uranium and the strong complexes of uranium(VI) with peroxide.

  • Effects of ionizing radiation and temperature on uranyl silicates: Soddyite (UO2)2(SiO4)(H2O)2 and uranophane Ca(UO2)2(SiO3OH)2 3.5H2O

     Sureda Pastor, Rosa Maria; Casas Pons, Ignasi; Gimenez Izquierdo, Francisco Javier; Pablo Ribas, Joan de; Quiñones Ruiz, Jose Miguel; Zhang, Jun-Ying; Ewing, R.C.
    Environmental science and technology
    Vol. 45, num. 6, p. 2510-2515
    DOI: 10.1021/es1041496
    Date of publication: 2011-03-15
    Journal article

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  • Sorption of strontium on uranyl peroxide: implications for a high-level nuclear waste repository

     Sureda Pastor, Rosa Maria; Rovira Boixaderas, Miguel Arcangel; Pablo Ribas, Joan de; Casas Pons, Ignasi; Gimenez Izquierdo, Francisco Javier; Martínez Lladó, Xavier
    Journal of hazardous materials
    Vol. 181, num. 13, p. 881-885
    DOI: 10.1016/j.jhazmat.2010.05.095
    Date of publication: 2010-09-15
    Journal article

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    Strontium-90 is considered the most important radioactive isotope in the environment and one of the most frequently occurring radionuclides in groundwaters at nuclear facilities. The uranyl peroxide studtite (UO2O2 center dot 4H(2)O) has been observed to be formed in spent nuclear fuel leaching experiments and seems to have a relatively high sorption capacity for some radionuclides. In this work, the sorption of strontium onto studtite is studied as a function of time. strontium concentration in solution and pH. The main results obtained are (a) sorption is relatively fast although slower than for cesium; (b) strontium seems to be sorbed via a monolayer coverage of the studtite surface, (c) sorption has a strong dependence on ionic strength, is negligible at acidic pH, and increases at neutral to alkaline pH (almost 100% of the strontium in solution is sorbed above pH 10). These results point to uranium secondary solid phase formation on the spent nuclear fuel as an important mechanism for strontium retention in a high-level nuclear waste repository (HLNW). (C) 2010 Elsevier B.V. All rights reserved.

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    Cadmium and lead removal from aqueous solution by grape stalk wastes: modeling of a fixed-bed column  Open access

     Miralles Esteban, Nuria; Valderrama Angel, Cesar Alberto; Casas Pons, Ignasi; Martínez Martínez, María R.; Florido Pérez, Antonio
    Journal of chemical and engineering data
    Vol. 55, num. 9, p. 3548-3554
    DOI: 10.1021/je100200w
    Date of publication: 2010-09
    Journal article

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    Grape stalk wastes generated in the wine production process were used for the removal of cadmium and lead ions from aqueous solutions. The experimental breakthrough curves (BTC) were obtained from fixedbed columns. Experiments were carried out to evaluate the influence of both inlet metal concentration and sorbent particle size. The experimental data were fitted to the Thomas model, a well-established fixed-bed sorption model. The theoretical sorption capacities obtained by the Thomas model were in good agreement with the breakthrough capacities determined from the sorption data. The CXTFIT code was used to determine the transport and sorption parameters of the convective-dispersive equation (CDE) and the two-site deterministic nonequilibrium (TSM/CDE) model by adjusting the models to the experimental breakthrough curves. The results showed that sorption capacities as well as both transport and sorption parameters were affected by the initial metal concentration as well as by the sorbent particle size.

  • Cesium sorption on studtite (UO2O2·4H2O)

     Gimenez Izquierdo, Francisco Javier; Rovira Boixaderas, Miguel Arcangel; Pablo Ribas, Joan de; Casas Pons, Ignasi; Sureda Pastor, Rosa Maria; Martínez Lladó, Xavier; Martínez Esparza, A.
    Radiochimica acta
    Vol. 98, num. 8, p. 479-483
    DOI: 10.1524/ract.2010.1742
    Date of publication: 2010
    Journal article

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  • Application of two sites non-equilibrium sorption model for the removal of Cu(II) onto grape stalk wastes in a fixed-bed column

     Florido Pérez, Antonio; Valderrama Angel, Cesar Alberto; Arévalo, Jaime A.; Casas Pons, Ignasi; Martínez Martínez, María R.; Miralles Esteban, Nuria
    Chemical engineering journal
    Vol. 156, num. 2, p. 298-304
    DOI: 10.1016/j.cej.2009.10.020
    Date of publication: 2010-01
    Journal article

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  • Modelling of the Ni(II) removal from aqueous solutions onto grape stalk wastes in fixed-bed column

     Valderrama Angel, Cesar Alberto; Arévalo, Jaime A.; Casas Pons, Ignasi; Martínez Martínez, María R.; Miralles Esteban, Nuria; Florido Pérez, Antonio
    Journal of hazardous materials
    Vol. 174, num. 1-3, p. 144-150
    DOI: 10.1016/j.jhazmat.2009.09.028
    Date of publication: 2010-02
    Journal article

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  • Combined effect of H2O2 and HCO3- on UO2(s) dissolution rates under anoxic conditions

     Casas Pons, Ignasi; Pablo Ribas, Joan de; Clarens Blanco, Frederic; Gimenez Izquierdo, Francisco Javier; Merino, J; Bruno, J.; Martínez Esparza, A.
    Radiochimica acta
    Vol. 97, num. 9, p. 485-490
    Date of publication: 2009
    Journal article

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  • Leaching of 53 MW/d kg U spent nuclear fuel in a flow-through reactor

     Serrano Purroy, D.; Clarens Blanco, Frederic; Glatz, J P; Wegen, D; Christiansen, B; Pablo Ribas, Joan de; Gimenez Izquierdo, Francisco Javier; Casas Pons, Ignasi; Martínez Esparza, A.
    Radiochimica acta
    Vol. 97, num. 9, p. 491-496
    DOI: 10.1524/ract.2009.1640
    Date of publication: 2009
    Journal article

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  • Stability of natural and syntehtic uranium (VI) peroxide hydrates under ionizing radiation

     Rey, Alexandra; Utsunomiya, Satoshi; Gimenez Izquierdo, Francisco Javier; Casas Pons, Ignasi; Ewing, Rodney C.; Pablo Ribas, Joan de
    American mineralogist
    Vol. 94, p. 229-235
    DOI: 10.2138/am.2009.2908
    Date of publication: 2009-01-01
    Journal article

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  • UTILIZACIÓN DE RESIDUOS IND. PARA LA DEPURACIÓN DE EFLUENTES CONTAMINADOS CON METALES PESADOS

     Miralles Esteban, Nuria; Martínez Martínez, María R.; Casas Pons, Ignasi; Florido Pérez, Antonio
    Competitive project

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  • Effect of HBS structure in fast release fraction of 48 GWd/tU PWR fuel

     Pablo Ribas, Joan de; Gimenez Izquierdo, Francisco Javier; Casas Pons, Ignasi; Clarens Blanco, Frederic
    International Materials Research Congress
    p. 613-620
    Presentation's date: 2009-05-26
    Presentation of work at congresses

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  • The role of uranium peroxide studtite on the retention of Cs, Sr and Se(VI)

     Pablo Ribas, Joan de; Gimenez Izquierdo, Francisco Javier; Casas Pons, Ignasi; Sureda Pastor, Rosa Maria; Rovira Boixaderas, Miguel Arcangel
    International Materials Research Congress
    p. 621-626
    Presentation's date: 2009-05-26
    Presentation of work at congresses

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  • Formación y Estabilidad de Fases Secundarias de UO2 en las condiciones de un almacenamiento Geológico profundo.

     Rey Cubero, Alexandra
    Department of Engineering Design, Universitat Politècnica de Catalunya
    Theses

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  • Effect of temperature on studtite stability: Thermogravimetry and differential scanning calorimetry investigations

     Rey, A; Casas Pons, Ignasi; Gimenez Izquierdo, Francisco Javier; Quiñones Ruiz, Jose Miguel; Pablo Ribas, Joan de
    Journal of nuclear materials
    Vol. 385, num. 2, p. 467-473
    Date of publication: 2009-03
    Journal article

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  • Stability of uranium (VI) peroxide hydrates under ionizing radiation

     Rey, A; Utsunomiya, S; Gimenez, J; Casas Pons, Ignasi; Pablo Ribas, Joan de; Ewing, Rc
    American mineralogist
    Vol. 94, num. 2-3, p. 229-235
    Date of publication: 2009-03
    Journal article

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  • Use of a fixed-bed column of grape stalk wastes for heavy metals removal from aqueous solutions

     Valderrama Angel, Cesar Alberto; Casas Pons, Ignasi; Martínez Martínez, María R.; Miralles Esteban, Nuria; Florido Pérez, Antonio
    European Meeting on Environmental Chemistry
    p. 34
    Presentation's date: 2009-12-04
    Presentation of work at congresses

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  • Secondary phase formation on UO2 in phosphate media

     Rey, A.; Gimenez Izquierdo, Francisco Javier; Casas Pons, Ignasi; Clarens Blanco, Frederic; Pablo Ribas, Joan de
    Applied geochemistry
    Vol. 23, num. 8, p. 2249-2255
    DOI: 10.1016/j.apgeochem.2008.03.008
    Date of publication: 2008-04-08
    Journal article

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    he dissolution of UO2 (a chemical analog of uraninite and of spent nuclear fuel) has been studied by using a flow-through reactor. The UO2 dissolution rates at total View the MathML source concentrations of 10−4, 10−5, and 10−6 mol dm−3 have been determined to be: 1.3 × 10−10 mol m−2 s−1, 6.7 × 10−11 mol m−2 s−1, and 2.0 × 10−11 mol m−2 s−1, respectively. The dissolution rates determined are found to be higher than the ones determined for similar carbonate concentrations. Moreover, the surface of the UO2 has been studied in static tests by means of the scanning force microscopy technique (SFM) in order to follow the formation of any secondary solid phase on its surface. The formation of chernikovite (H2(UO2)2(PO4)2 · 8H2O) has been observed at a 10−4 M total View the MathML source concentration, while no uranyl-phosphate secondary phases have been found at lower View the MathML source concentrations. In experiments performed in the presence of both carbonate and phosphate, no precipitation of secondary phases has been observed. It is postulated that this is due to the formation of the highly stable uranyl-carbonate complexes in solution.

  • EFFECT OF TEMPERATURE ON STUDTITE STABILITY. TG and DSC experiments

     Casas Pons, Ignasi
    E-MRS
    Presentation's date: 2008-01-01
    Presentation of work at congresses

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  • Determination of UO2(s) dissolution rates in a hydrogen peroxide medium as a function of pressure and temperature

     Casas Pons, Ignasi; Borrell Matas, Marc; Sanchez, L; Pablo Ribas, Joan de; Gimenez Izquierdo, Francisco Javier; Clarens Blanco, Frederic
    Journal of nuclear materials
    Vol. 375, num. 1, p. 151-156
    Date of publication: 2008-03
    Journal article

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  • Grape stalks waste as low cost biosorbents: An alternative for metal removal from aqueous solutions

     Miralles Esteban, Nuria; Martínez Martínez, María R.; Florido Pérez, Antonio; Casas Pons, Ignasi; Fiol Santaló, Núria; Villaescusa, I
    Solvent extraction and ion exchange
    Vol. 26, num. 3, p. 261-270
    Date of publication: 2008-06
    Journal article

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  • UO2 dissolution in the presence of hydrogen peroxide at pH>11

     Meca, S; Marti Gregorio, Vicenç; Pablo Ribas, Joan de; Gimenez Izquierdo, Francisco Javier; Casas Pons, Ignasi
    Radiochimica acta
    Vol. 96, num. 9-11, p. 535-539
    Date of publication: 2008-09
    Journal article

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  • Sorption of cesium on freshly precipitated studtite (UO4¿4H2O). Kinetics and sorption and sorption isotherm

     Gimenez Izquierdo, Francisco Javier; Rovira Boixaderas, Miguel Arcangel; Pablo Ribas, Joan de; Casas Pons, Ignasi; Martínez-Esparza, A
    MOBILE FISSION AND ACTIVATION PRODUCTS IN NUCLEAR WASTE DISPOSAL
    p. 55-64
    Presentation of work at congresses

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  • KINETICS OF UO2(s) DISSOLUTION IN THE PRESENCE OF HYPOCHLORITE, CHLORITE AND CHLORATE SOLUTIONS

     Sureda, R; Casas Pons, Ignasi; Gimenez Izquierdo, Francisco Javier; Pablo Ribas, Joan de
    MRS Symposium: Scientific basis for nuclear waste managementEMENT
    p. 599-604
    Presentation of work at congresses

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  • Valorització de residus vegetals procedents de processos industrials com biosorbentes per a l'elimincio d'ions mettlaics d'afleuntes aquosos

     Casas Pons, Ignasi; Fiol Santaló, Núria; Florido Pérez, Antonio; Martínez Martínez, María R.; Miralles Esteban, Nuria; Villaescusa, I
    Congrés UPC Sostenible 2015
    p. 1-2
    Presentation of work at congresses

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  • Rn fractional release of high-burnup fuel:effect of hbs and estimation of accesible grain boundary

     Clarens Blanco, Frederic; Serrano-Purroy, D; Martínez-Esparza, A; Wegen, D; Gonzalez-Robles, E; Pablo Ribas, Joan de; Casas Pons, Ignasi; Gimenez Izquierdo, Francisco Javier; Christiansen, B; Glatz, J P
    MRS Symposium: Scientific basis for nuclear waste managementEMENT
    p. 439-446
    Presentation of work at congresses

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  • Stability of synthetic uranium(VI) peroxide hydrates under ionizing radiation

     Casas Pons, Ignasi
    Migration 2007
    Presentation's date: 2007-01-01
    Presentation of work at congresses

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  • MAGNETITE SORPTION CAPACITY FOR STRONTIUM AS A FUNCTION OF pH

     Pablo Ribas, Joan de; Rovira Boixaderas, Miguel Arcangel; Gimenez Izquierdo, Francisco Javier; Casas Pons, Ignasi; Clarens Blanco, Frederic
    MRS Symposium: Scientific basis for nuclear waste managementEMENT
    p. 593-598
    Presentation of work at congresses

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  • Sorption of cesium on freshly precipitated studtite (UO4·4H2O). Kinetics of sorption and sorption isotherm

     Casas Pons, Ignasi
    International Workshop on Mobile Fission and Activation Products in Nuclear Waste Disposal
    Presentation's date: 2007-01-11
    Presentation of work at congresses

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  • The use of a high-FeO olivine as a redox buffer in a nuclear waste repository

     Gimenez Izquierdo, Francisco Javier; Rovira Boixaderas, Miguel Arcangel; Clarens Blanco, Frederic; Casas Pons, Ignasi; Duro Pérez, Lara; Grivé, M; Bruno Salgot, Jorge; Pablo Ribas, Joan de
    Journal of contaminant hydrology
    Vol. 83, p. 42-52
    Date of publication: 2006-06
    Journal article

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  • Modelling of the spent fuel dissolution rate evolution for repository conditions. Matrix Alteration Model results and sensitivity analyisis

     Quiñones Ruiz, Jose Miguel; Martínez-Esparza, A; CERA, E; Merino, J; BRUNO, J; Pablo Ribas, Joan de; Casas Pons, Ignasi; Gimenez Izquierdo, Francisco Javier; Clarens Blanco, Frederic; Rovira Boixaderas, Miguel Arcangel
    Materials Research Society Symposium
    p. 433-440
    Presentation of work at congresses

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  • VCHEM, Progama de càlcul d'equilibris químics. Aplicació a les assignatures de primer, segon i tercer cicle

     Casas Pons, Ignasi
    Segona Jornada sobre Didàctica i Organització d´Assignatures Basades en l´Experimentació
    Presentation's date: 2005-02-10
    Presentation of work at congresses

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  • Role of hydroxyl radicals during oxidative dissolution of UO2 by hydrogen peroxide

     Pablo Ribas, Joan de; Clarens Blanco, Frederic; Casas Pons, Ignasi; Giménez, J; Rovira, M
    Materials Research Society Symposium
    Presentation of work at congresses

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  • Sorption of Molybdenum(VI) on Synthetic Magnetite

     Rovira Boixaderas, Miguel Arcangel; Casas Pons, Ignasi; Pablo Ribas, Joan de; Gimenez Izquierdo, Francisco Javier; Clarens Blanco, Frederic; Martínez-Lladó, X; Martínez Lladó, Xavier
    Materials Research Society Symposium
    p. 143-150
    Presentation of work at congresses

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  • Chemical durability and performance of assessment of spent fuel and high level waste forms under simulated repository conditions-Spanish contribution to IAEA project

     Martínez-Esparza, A; Gago, J A; Quiñones Ruiz, Jose Miguel; Iglesias, E; CERA, E; Merino, J; Pablo Ribas, Joan de; Casas Pons, Ignasi
    Materials Research Society Symposium
    p. 283-290
    Presentation of work at congresses

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  • Radiolytic modelling of spent fuel oxidative dissolution mechanism. Development of the model and testing with experimental data

     Casas Pons, Ignasi
    Migration 2005
    Presentation's date: 2005-01-01
    Presentation of work at congresses

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  • SFM study of the secondary phase formation on UO2 in contact with phosphate solutions

     Casas Pons, Ignasi
    Migration 2005
    Presentation's date: 2005-01-01
    Presentation of work at congresses

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  • Equilibris químics en dissolució

     Aguilar Sanjuan, Manuel; Casas Pons, Ignasi; Cortina Pallas, Jose Luis; Farran Marsa, Adriana; Florido Pérez, Antonio; Gimenez Izquierdo, Francisco Javier; Martínez Martínez, María R.; Miralles Esteban, Nuria; Pablo Ribas, Joan de; Sastre Requena, Ana Maria
    Date of publication: 2005-09
    Book

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  • Development of a Matrix Alteration Model (MAM)

     Martínez, A Esparza; Cuñado, M A; Gago, J A; Quiñones Ruiz, Jose Miguel; Iglesias, E; Cobos, J; González, A De La Huebra; CERA, E; Merino, J; BRUNO, J; Pablo Ribas, Joan de; Casas Pons, Ignasi; Clarens Blanco, Frederic; Gimenez Izquierdo, Francisco Javier
    ENRESA: Empresa Nacional de Residuos Radiactivos
    p. 1-101
    Date of publication: 2005-01
    Journal article

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  • The dissolution of high-FeO olivine rock from the Lovasjärvi intrusion (SE-Finland) at 25ºC as a function of pH

     Duro Pérez, Lara; El Aamrani, Fatima Zohra; Rovira Boixaderas, Miguel Arcangel; Gimenez Izquierdo, Francisco Javier; Casas Pons, Ignasi; Pablo Ribas, Joan de; Bruno Salgot, Jorge
    Applied geochemistry
    Vol. 20, p. 1284-1291
    Date of publication: 2005-07
    Journal article

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