Recent sediments dating using short-lived radionuclides

[ES] Se presentan las características principales del método de datación de sedimentos recientes mediante el radioisótopo natural 210Pb y su validación utilizando radionucleidos artificiales tales como 137Cs y 239,240Pu. Se hace una revisión de los principios generales de esta metodología, se aportan recomendaciones prácticas para la recogida de testigos sedimentarios en el campo y su posterior procesamiento en el laboratorio, se describen diferentes técnicas analíticas utilizadas en la determinación de sus concentraciones y se explican brevemente varios modelos para la interpretación de los perfiles obtenidos. Por último, se incluyen ejemplos prácticos de su aplicación en secuencias sedimentarias procedentes de distintos ambientes marinos (estuario, bahía y plataforma continental) en el norte de la Península Ibérica.[EN] The main characteristics of the dating method of recent sediments using the natural radioisotope 210Pb and its validation with artificial radionuclides such as 137Cs and 239,240Pu are presented. A review of the general principles of this methodology is made, practical recommendations for the collection of sedimentary cores in the field and their subsequent processing in the laboratory are provided, several analytical techniques used to measure their concentrations are described and several models for the interpretation of the profiles are briefly explained. Finally, practical examples of its application in sedimentary sequences from different marine environments (estuary, bay and continental shelf) in the northern Iberian Peninsula are also included.Este artículo se ha inspirado en el manual de referencia publicado por Sanchez-Cabeza, J.A., Díaz-Asencio, M., Ruiz-Fernández, A.C., eds. (2012). Radiocronología de sedimentos costeros utilizando 210Pb: Modelos, Validación y Aplicaciones. Organismo Internacional de Energía Atómica, Viena, 105 pp., donde se profundizan diferentes aspectos tratados aquí. Trabajo financiado por los proyectos RTI2018-095678-B-C21, MCIU/AEI/FEDER, UE (MINECO) e IT976-16 (EJ/GV). Dos revisoras/es anónimas/os mejoraron el manuscrito original con sus comentarios y sugerencias. Contribución nº 56 de la Unidad de Investigación Geo-Q Zentroa (Laboratorio Joaquín Gómez de Llarena).Cearreta, A.; Gómez-Arozamena, J.; Irabien, M.; Ruiz-Fernández, A.; Sanchez-Cabeza, J.; Ortiz Moragón, J.; Sáez-Muñoz, M. (2022). Datación de sedimentos recientes utilizando radionucleidos de vida corta. Cuaternario y Geomorfología. 36(3-4):87-104. https://doi.org/10.17735/cyg.v36i3-4.9350487104363-

Nanofiltration separation of polyvalent and monovalent anions in desalination brines

This work, as part of a global membrane process for the recovery of alkali and acids from reverse osmosis (RO) desalination brines, focuses on the nanofiltration (NF) separation of polyvalent and monovalent anions, more specifically sulfate and chloride. This pretreatment stage plays a key role in the whole recovery process. Working with model brines simulating the concentration of RO concentrates, 0.2–1.2 M chloride concentration and 0.1 M sulfate concentration, the experimental performance and modeling of the NF separation is reported. The study has been carried out with the NF270 (Dow Filmtec) membrane. The effect of operating pressure (500–2000 kPa), ionic strength (0.4–1.3 M) and chloride initial concentration (0.2–1.2 M) on the membrane separation capacity has been investigated. Finally, the Donnan Steric Pore Model (DSPM) together with experimentally determined parameters, effective pore radius (rp), thickness of the membrane effective layer (d) and effective membrane charge density (Xd), was proved accurate enough to satisfactorily describe the experimental results. In this work we provide for the first time the analysis of partitioning effects and transport mechanism in the NF separation of sulfate and chloride anions in concentrations that simulate those found in RO desalination brines.This work has been financially supported by projects CTQ2008-0690, ENE2010-15585 and CTM2011-23912 (co-financed by ERDF Funds).The authors would like to acknowledge SADYT, S.A. for providing assistance for this work

Long-range magnetic ordering in magnetic ionic liquid: Emim[FeCl 4]

Up to now most of the magnetic ionic liquids containing tetrachloroferrate ion FeCl4 have evidenced a paramagnetic temperature dependence of the magnetic susceptibility, with only small deviations from the Curie law at low temperatures. However, we report on the physical properties of 1-ethyl-3-methylimidazolium tetrachloroferrate Emim[FeCl4], that clearly shows a long-range antiferromagnetic ordering below the Néel temperature TN≈3.8K. In addition, the field dependence of the magnetization measured at 2K is characterized by a linear behaviour up to around 40kOe, while above this field the magnetization becomes saturated with a value of 4.3 μB/Fe, which is near the expected fully saturated value of 5 μBs/Fe for an Fe3 + ion