Cyclic Voltammetric Experiment - Simulation. Comparisons of the Complex Mechanism Associated with Electrochemical Reduction of Zr4+ in LiCl-KCl Eutectic Molten Salt

Nuclear energy increasingly represents an important option for generating largely clean CO2-free electricity and zirconium is a fission product that is expected to be present in irradiated fuels. The present investigation addresses the electrochemical reduction of Zr4+ to Zro in LiCl - KCl eutectic molten salt in the temperature range 425–550◦C using cyclic voltammetry (CV), square-wave voltammetry (SWV) and bulk electrolysis. Simulations of the CV data indicate that the initial reduction proceeds through surface confined steps: Zr4+* + 2e− ↔Zr2+* and Zr2+* + 2e− ↔Zr* processes (* adsorbed species) followed by a peak-shaped complex diffusion controlled step that consists of a combination of closely spaced processes associated with the reactions Zr4+ + 4e− →Zr and Zr4+ + 3e− →Zr+*. Zr+*, probably in the form of ZrCl* is then further reduced to Zro* at even more negative potentials. The simulations provide the first quantitative analysis of the thermodynamics and kinetics of the Zr4+ reduction in the LiCl-KCl eutectic

Experimental and simulation study of the electrode reaction mechanism of La3+ in LiCl-KCl eutectic molten salt

Nuclear energy increasingly represents an important option for generating largely clean CO2-free electricity. The present investigation addressed the electrochemical reduction of La3+, a rare earth element, in LiCl - KCl eutectic molten salt in the temperature range 450–550°C using transient techniques such as cyclic voltammetry (CV) and square-wave voltammetry (SWV). Simulation of the CV data suggested a reaction mechanism in which lanthanum reduction occurred in a single three-electron step (La3+ + 3e− → La°). The rate constant, k° was determined to be 5.7 x 10−3, 14.6 x 10−3 and 31.7 x 10−3 cm/s and the Matsuda et al.1 dimensionless parameter Ʌ was 0.82, 1.52 and 2.89 for temperatures of 450, 500 and 550°C, respectively and therefore it was concluded that the was process quasi reversible

On the formation of U-Al alloys in the molten LiCl-KCl eutectic

U-Al alloy formation has been studied in the temperature range of 400 – 550 °C by electrochemical techniques in the molten LiCl-KCl eutectic. Cyclic voltammetry showed that underpotential reduction of U(III) onto solid Al occurs at a potential about 0.35 V more anodic than pure U deposition. Open circuit potential measurements, recorded after small depositions of U metal onto the Al electrode, did not allow the distinction between potentials associated with UAlx alloys and the Al rest potential, as they were found to be practically identical. As a consequence, a spontaneous chemical reaction between dissolved UCl3 and Al is thermodynamically possible and was experimentally observed. Galvanostatic electrolyses were carried out both on Al rods and Al plates. Stable and dense U-Al deposits were obtained with high faradic yields, and the possibility to load the whole bulk of a thin Al plate was demonstrated. The analyses (by SEM-EDX and XRD) of the deposits indicated the formation of different intermetallic phases (UAl2, UAl3 and UAl4) depending on the experimental conditions

Extracción de Au(CN)2 mediante la amina primene 81R y mezclas sinérgicas de ésta con los derivados organofosforados neutros cyanex 923 y cyanex 921

La recuperación de oro de disoluciones cianuradas tradicionalmente se ha realizado mediante cementación, adsorción en carbón o cambio ionico. Sin embargo, la técnica de la extracción con disolventes no se ha empleado con la misma asiduidad en este campo, pese a las posibilidades que presenta para separar y concentrar el metal de interés. En la presente memoria de tesis doctoral se aborda el estudio de la recuperación de oro de disoluciones en medio cianuro mediante la técnica de extracción con disolventes, con objeto de evaluar las posibilidades que presenta la misma para la recuperación de este metal precioso. Con este objeto se emplean tres nuevos agentes de extracción de nueva utilización en este campo, como son la amina primaria de nombre comercial primene 81r y los óxidos de fosfina también comerciales cyanex 923 y cyanex 921.Depto. de Ingeniería Química y de MaterialesFac. de Ciencias QuímicasTRUEpu

La orientación académica y profesional en el alumnado con trastornos del espectro autista

Promueve la Dirección General de Innovación Educativa y Atención a la Diversidad de la Consejería de Educación y Universidades.La orientación académica y profesional forma parte inseparable del proceso de atención educativa al alumnado; y debe serlo aún más cuando el alumno presenta necesidades educativas especiales aso‐ciadas a Trastornos del Espectro del Autismo. En efecto, este alum‐nado no sólo requiere ‐de una manera más o menos intensa‐ de adaptaciones del currículo, o de los diferentes elementos del mismo, sino también una cuidadosa actuación que le oriente a lo largo de todo el proceso educativo y, sobre todo, en los momentos previos a la adopción de decisiones respecto a los diferentes itinerarios educativos. Este es el objetivo básico de esta publicación.Consejería de Educación y Universidades; Avda. La Fama, 15; 30006, Murcia; Teléfono 968 279842; [email protected]; www.educarm.es/publicacionesES

Alteration in Rhizosphere Soil Properties of Afforested Rhamnus lycioides Seedlings in Short-Term Response to Mycorrhizal Inoculation with Glomus intraradices and Organic Amendment

9 pages, 5 tables, 1 figure.The reestablisment of autochthonous plant species is an essential strategy for recovering degraded areas under semiarid conditions. A field experiment was carried out to assess the short-term effect of two reafforestation methods involving mycorrhizal inoculation and compost addition on soil quality parameters and Rhamnus lycioides seedling growth. The nutrient content (NPK) and enzymatic activities (dehydrogenase, urease, protease-BAA, acid phosphatase and β-glucosidase) increased and bulk density decreased in the rhizosphere soil with the organic amendment. Biomass C of rhizosphere soil increased by at least 240% with respect to the control soil after mycorrhizal inoculation and the combination of compost addition + mycorrhizal inoculation. Both mycorrhizal inoculation and composted organic residue addition increased R. lycioides seedling growth in the same proportion. In the short term, we conclude that the application of both reafforestation methods not only enhances the establishment of R. lycioides seedlings, but also improves soil quality.This research was supported by the EC CICYT cofinanced FEDER program (1FD97-0507 FOREST). F. Caravaca acknowledges a grant from the European Commission (HPMF-CT-2000-00822).Peer reviewe