Remoción de flúor en agua con zeolitas naturales mexicanas

96 páginas. Maestría en Ciencias e Ingeniería Ambientales.La problemática del flúor en México puede ser considerada crítica, puesto que no en todos los estados de México se han realizado estudios a las aguas subterráneas o pozos de donde es extraída el agua potable. Por lo anterior, el objetivo principal de éste trabajo fue evaluar la viabilidad del uso de las zeolitas naturales para la eliminación de fluoruros presentes en aguas subterráneas, que es destinada al consumo humano, así como, valorar el acondicionamiento de las zeolitas con soluciones de calcio, manganeso o hierro y su eficiencia como material adsorbente en dos sistemas de columna de lecho fijo, uno de flujo ascendente y otro de flujo descendente, proponer el tratamiento de acondicionamiento más adecuado a la zeolita en base a la eficacia, así como, designar los parámetros de operación, determinar la capacidad de adsorción de las zeolitas naturales y acondicionadas a través de isotermas de adsorción y proponer una alternativa para la disposición del residuo generado

Caracterización y acondicionamiento de zeolitas mexicanas con calcio para ser usados como materiales adsorbentes

En este trabajo se presenta la caracterización de zeolitas naturales mexicanas y su acondicionamiento con calcio para el proceso de adsorción usando cinco zeolitas naturales recolectadas en yacimientos de diferentes municipios del estado de Oaxaca, México. Los resultados de caracterización mostraron que las zeolitas tienen estructura tipo clinoptilolita y están presentes diferentes cationes en su estructura, las cuales fueron lavadas para eliminar impurezas e intercambiadas con solución de sodio 2 M y una de ellas se seleccionó para ser acondicionada con solución de calcio, para esta zeolita los resultados de caracterización por SEM/EDS, XRD y FTIR mostraron que la estructura tras el acondicionamiento no se modificó y que el contenido de calcio se vio incrementado.This work presents the characterization of Mexican natural zeolites and their conditioning with calcium for the adsorption process using five natural zeolites collected from different municipalities in the state of Oaxaca, Mexico. The characterization results showed that the zeolites have clinoptilolite type structure and different cations are present in their structure, which were washed to remove impurities and exchanged with 2 M sodium solution and one of them was selected to be conditioned with calcium solution, for this zeolite the characterization results by SEM / EDS, XRD and FTIR showed that the structure after the conditioning was not modified and that the calcium content was increased

Zeolita natural tipo clinoptilolita acondicionada con hierro

En el suelo de la República Mexicana se encuentra una gran variedad de materiales zeolíticos, los cuales se consideran materiales locales de fácil adquisición y económicos que se han usado en un sinfín de aplicaciones, dadas las propiedades que tienen este tipo de materiales cristalinos. En el presente trabajo se presenta el acondicionamiento de dos zeolitas naturales mexicanas, tipo clinoptilolita de dos estados de la República Mexicana: Oaxaca y Guanajuato. Las zeolitas se acondicionaron con hierro por el método de precipitación-impregnación a partir de una solución de nitrato de hierro. Las zeolitas se caracterizaron por los métodos de Difracción de Rayos X (XRD), Microscopia Electrónica de Barrido (SEM), Análisis Químico Elemental (SEM/EDS), Espectroscopía Raman y Espectroscopía de Infrarrojo por Transformada de Fourier (FT-IR), y estos resultados mostraron que el acondicionamiento con hierro fue bueno para ambas zeolitas naturales. Dichos materiales se pretenden usar en un futuro, como adsorbentes de especies contaminantes en agua.On the floor of the Mexican Republic there is a great variety of zeolitic materials, which are considered easy-to-buy and cheap local materials that have been used in countless applications, given the properties of this type of crystalline materials. This paper presents the conditioning of a natural Mexican zeolite (clinoptilolite type) from two states of the Mexican Republic: Oaxaca and Guanajuato. The zeolite was conditioned with iron by the precipitation-impregnation method from an iron nitrate solution. The zeolites were characterized by the methods of X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Elemental Chemical Analysis (SEM/EDS), Raman Spectroscopy and Fourier Transformed Infrared Spectroscopy (FT-IR) and these results showed that iron conditioning was good for both natural zeolites. These materials are intended to be used in the future, as adsorbents of water-polluting species

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Removal of Fluoride in Water with Mexican Natural Zeolite

This work presents the results of the fluoride removal in water, through an adsorption process with the use of a natural Mexican zeolite conditioned with calcium, manganese or iron in a fixed bed column system. The XRD and FTIR characterization results demonstrated that the conditioning modifies the surface chemical composition of the zeolite and the SEM/EDS analysis corroborates the increase of the exchanged ions. The conditioning of the zeolite generated an increase in the adsorption capacity of fluorine, the best percentage of removal obtained from fluoride ions was 98%, for a water with a concentration of 10 mg·L−1 with the conditioned zeolite with iron.</b

New perylene-doped polymeric thin films for efficient and long-lasting lasers

We establish an efficient strategy to optimize the performance of dye-doped host materials consisting of analyzing in a systematic way the dependence of their Amplified Spontaneous Emission (ASE) efficiency and photostability on the composition and structure of the matrices, selected to specifically avoid the thermal and/or chemical (photooxidation) processes, main mechanisms of dye photodegradation. For this study, a number of experimental polyimides have been chosen as a host matrix and their behavior has been compared with that of poly(methyl methacrylate) (PMMA). We correlate the optical properties with the oxygen permeation and thermal properties of the different polymeric hosts doped with perylene dyes to deepen the understanding of the photodegradation mechanism predominant in these dyes and to minimize its influence. We demonstrate high efficiency and photostable ASE from waveguides based on polymeric materials doped with Perylene Orange (PO), Perylene Red (PR), and mixtures of both. This enhancement in the optical properties allows reaching high gain and long-lasting distributed feedback (DFB) laser emission based on PO doped polymer matrices, even when operating in an unoptimised resonator.Peer Reviewe

Memorias del primer Simposio Nacional de Ciencias Agronómicas

Primer simposio nacional de Ciencias Agronómicas: El renacer del espacio de discusión científica para el Agro colombiano

Memorias del primer Simposio Nacional de Ciencias Agronómicas

Primer simposio nacional de Ciencias Agronómicas: El renacer del espacio de discusión científica para el Agro colombiano