900 research outputs found

    DESARROLLO DE UN PROCESO DE SEPARACION Y RECUPERACION DE POLIMERO-ALUMINIO UTILIZANDO ACEITE RECICLADO, A PARTIR DE PELICULAS DE DESECHO RESULTANTES DE LA RECUPERACION DE CELULOSA EN EMPAQUES FLEXIBLES DE REPORTE DE INVESTIGACION

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    El presente proyecto surge con la necesidad de responder y dar solución a un problema de procesamiento y recuperación de aluminio y polímero que actualmente presenta la industria de recuperación de celulosa a partir de los envases tipo tetra pak para la producción de papel, y su posterior venta en las empresas papeleras como Kimberly & Klark entre otras. Todos los residuos que resultan después de la recuperación de la celulosa (papel) de este tipo de envases, son películas de aluminio y polímero, que resultan difíciles de separar porque se adhieren a través de adhesivos y extrución. Por lo que la separación mecánica no es una opción y se requiere el desarrollo de un nuevo proceso para una separación efectiva y de bajo costo. En este sentido el objetivo de este proyecto es el desarrollo de un nuevo proceso de separación del polímero y del aluminio para su posterior reciclaje. En este proyecto se propuso la utilización de un solvente que fuera lo mas barato posible y además que pudiera evitar contaminación ambiental, con este propósito se propuso utilizar aceite de canola reciclado (aceite de los restaurante que no utilizan o que ya no es útil para ellos y que tiran) , debido a su alta polaridad y posible disolución del polímero en este debido a esta propiedad

    Nanoporous Materials for Carbon Dioxide Separation and Storage

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    Global climate change is one of the most challenging problems that human beings are facing. The large anthropogenic emission of CO2 in the atmosphere is one of the major causes for the climate change. Coal-fired power plants are the single-largest anthropogenic emission sources globally, accounting for approximately one third of the total CO2 emissions. It is therefore necessary to reduce CO2 emission from coal-fired power plants. Current technologies for the post-combustion CO2 capture from flue gas streams can be broadly classified into the three categories: absorption, adsorption, and membrane processes. Despite challenges, CO2 capture by adsorption using solid sorbents and membranes offers opportunities for energy-efficient capture and storage of CO2. Nanoporous materials have attracted tremendous interest in research and development due to their potential in conventional applications such as catalysis, ion-exchange, and gas separation as well as in advanced applications such as sensors, delivery, and micro-devices. In the first part of this dissertation, we will study the synthesis of membranes using an emerging class of nanoporous materials, metal-organic frameworks (MOFs) for carbon dioxide (CO2) separations. Due to the unique chemistry of MOFs which is very different from that of zeolites, the techniques developed for the synthesis of zeolite membranes cannot be used directly. In order to overcome this challenge, a couple of novel techniques were developed: 1) "thermal seeding" for the secondary growth and 2) "surface modification" for the in situ growth. Membranes of HKUST-1 and ZIF-8, two of the most important MOFs, were prepared on porous α-alumina supports using thermal seeding and the surface modification techniques, respectively. The second part of this dissertation demonstrates a simple and commercially viable application of nanoporous materials (zeolite 5A and amine-functionalized mesoporus silica), storing CO2 as a micro-fire extinguishers in polymers. Materialist is observed that by dispersing these highly CO2-philic nanoporous materials in polymer matrices, the propagation of flame was greatly retarded and extinguished. This flame retarding behavior is attributed to the fact that CO2 released from the sorbents (zeolite 5A and mesoporous silica), blocks the flow of oxygen, therefore causing the fire to be effectively extinguished. Our results suggest that the binding strength of CO2 on sorbents play an important role. If the binding strength of CO2 is too low, CO2 releases too early, thereby ineffective in retarding the flame

    Facile synthesis of Cd-substituted zeolitic-imidazolate framework Cd-ZIF-8 and mixed-metal CdZn-ZIF-8

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    scientific paperZeolitic-imidazole framework ZIF-8 has attracted tremendous interests for the highresolution kinetic separation of propylene/propane mixture due to its effective aperture size in between the sizes of propylene and propane molecules. It is of great interest to fine-tune the effective aperture size of ZIF-8 either to improve its propylene/propane separation performances or to extend its use to the separation of other gas mixtures. It has been shown that substituting Zn with other metal nodes (e.g. Co) is a potential means to fine-tune the effective aperture size of ZIF-8. Here, we attempt to introduce another metal center, Cd, into ZIF-8 in a facile and scalable manner. Phase-pure Cd-ZIF-8 was successfully synthesized in methanol using a conventional solvothermal method, although it showed a narrow synthesis window. The presence of an organic base (triethylamine, TEA) was found critical not only for the facile synthesis of phase-pure Cd- ZIF-8 but also for the suppression of its phase transformation. A battery of characterizations including single-crystal X-ray structure solutions confirmed that the effective aperture size of Cd-ZIF-8 is the largest among its iso-structures (Zn-ZIF-8 and Co-ZIF-8). Finally, for the first time, mixed-metal CdZn-ZIF-8 crystals with various Cd/Zn ratios were solvothermally synthesized, demonstrating a further opportunity for varying the effective aperture sizes of ZIF-8 and its iso-structures.National Science Foundation Qatar National Research Fund Texas A&M Engineering Experimental Station

    Double aluminum recovery and its reuse in wastewater treatment

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    This work evaluates the use of aluminum contained in the aluminum–polyethylene films as anodic electrodes using the electrocoagulation technique to reduce the pollutant contents of industrial wastewater quickly and effectively. Thermal treatment at 500 °C produces pure aluminum (according to TGA and SEM/EDS analysis) which is used to construct aluminum disks (applying 6 tons/cm2 of pressure). Aluminum disks are used as cathodes and anodes in an electrochemical cell. The current density applied in the recovered Al electrodes was 12 mA cm−2, and the maximum COD reduction of wastewater was 77 % at 25 min of treatment. The color and turbidity reductions are 87 and 90 %, respectively. The resulting sludge of wastewater treatment was thermally treated and a second aluminum recovery was reached; since the organic material present in the sludge was removed by the high temperature, the obtained aluminum was pure enough for its reuse. The use of aluminum–polyethylene films as electrodes in the electrocoagulation process contributes to the pollutant removal without the addition of chemical reagents or changing the pH, so it is both effective and environmentally friendly.UAEM-UNAM CONACY

    síntesis, caracterización y aplicaciones

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    La Nanotecnología es un área de la ciencia relativamente nueva. No obstante, una gran parte de la comunidad científica considera que es la base del desarrollo tecnológico de los próximos años. Dentro del campo de estu dio de la nanotecnología encontramos las nanoestructuras metálicas. Estos nanomateriales presentan propiedades muy interesantes y diferentes a los materiales “en bulto” o a escala macroscópica; entre ellas, la conductividad eléctrica y las propiedades magnéticas, ópticas y de catálisis, propiedades que las hacen candidatas a innumerables aplicaciones en todos los campos de la tecnología. Desafortunadamente, como suele suceder en muchos ámbitos de la ciencia y la tecnología, es la comunidad científica que estudia un área concreta quien conoce en exclusiva esa información. Por ello, nuestro grupo de investigación ha escrito este libro intentando cum Nanoestructuras metálicas: síntesis, caracterización y aplicaciones viii plir dos objetivos principales: el primero, dar a conocer los últimos resultados de nuestras investigaciones con nanoestructuras metálicas y algunas de sus aplicaciones, dicha información va dirigida a la comunidad científica interesada en el área; el segundo objetivo es redactar un libro que sea útil para quienes estén interesados en esta ciencia aunque no tengan demasiada experiencia en el tema, para ello, cada capítulo cuenta con una parte introductoria en la que se presentan aspectos generales del tema que se trata. A su vez, se ha intentado emplear un lenguaje de fácil comprensión pero sin que se pierda la especificidad de cada tema. Finalmente, los autores de este libro queremos agradecer a nuestra alma mater, la Universidad Autónoma del Estado de México, por el apoyo recibido para la publicación del mismo, esperando poder contribuir así al fortalecimiento del área científica.El desarrollo de la tecnología siempre ha estado íntimamente relacionado con las necesidades del ser humano por controlar su entorno y los fenómenos naturales, esto con el objeto de lograr una mejor calidad de vida para las personas. Muchos de los descubrimientos científicos más importantes, como es el caso de las leyes de Newton o la teoría de la relatividad de Einstein, revolucionaron la tecnología dando paso a una nueva era, en la que todo se explica desde el principio fundamental de los átomos. Ello provocó que científicos como Richard Feyman, ganador del Premio Nobel de Física en 1965, empezaran a vislumbrar las posibilidades que presentaba la nanotecnología. Feyman mencionó que, al poder estudiar y entender el comportamiento de los átomos y las moléculas, se podrían interpretar de mejor manera los fenómenos en el universo, dando paso a la frase: “En el fondo hay espacio de sobra”

    Use of recycled aluminum - polyethylene composite films as anodic electrodes for electrocoagulation of wastewater

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    artículo para uso de películas de aluminio polietilenoThis work evaluates the use of aluminum contained in the aluminum-polyethylene films as anodic electrodes using the electrocoagulation technique to reduce the pollutants contents of an industrial wastewater quickly and effectively. Two different current densities were applied 25 and 12.5 mA cm-2. When the current density of 25 mA cm-2 is used, the aluminum electrodes reduce the COD of wastewater by about 65% and the aluminum-polyethylene films electrodes reduces the COD by 56%. The color and turbidity reductions are 87 and 90% respectively. The use of aluminum-polyethylene films as electrodes in the electrocoagulation process contributes to the pollutant removal without the addition of chemical reagents or changing the pH, so it is both effective and environmentally friendly.Centro Conjunto de Investigación en Química Sustentable, UAEM-UNAM, CONACYT, UAEMe

    Solvent effect in the polyethylene recovery from multilayer postconsumer aseptic packaging

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    articuloPolyethylene films were separated and recovered from polyethylene–aluminum composites derived from recycling multilayer postconsumer aseptic packaging. A brief study about the separation process by dissolving PE–aluminum (PE–Al) composites into a series of organic solvents with a combination of time and temperature is presented. Through this procedure, 56% polyethylene is recovered from this kind of composites in optimized conditions. DSC and TGA studies were performed to determine the thermal stability of recovered polyethylene films and to establish a comparison with a PE reference commercial product, demonstrating that recovered polyethylene films kept their thermal properties.SIEA-UAEMEX (Project No. 3410/ 2013 M) and CONACYT (Project No. 135053

    SEM, AFM and CLSM microscopic techniques as tools for characterization of cellulose, polyaluminum and aluminum recovered from Tetra Pak packaging

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    In this chapter, the characterization of the morphological features of sub-products of Tetra Pak packaging using SEM, AFM and CLSM microscopic techniques is presented. In a first step, the separation of the components of the Tetra Pak was done using hydropulping mechanical process; the principal obtained products include cellulose, aluminium and polyethylene+aluminum. The last one called Polyaluminum. After this, the morphological analysis was obtained. The results show that such microscopy techniques are adequate for describe the high degree of purity of the components after recycling

    Waste Cellulose from Tetra Pak Packages as Reinforcement of Cement Concrete

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    The development of the packaging industry has promoted indiscriminately the use of disposable packing as Tetra Pak, which after a very short useful life turns into garbage, helping to spoil the environment. One of the known processes that can be used for achievement of the compatibility between waste materials and the environment is the gamma radiation, which had proved to be a good tool for modi cation of physicochemical properties of materials. The aim of this work is to study the e ects of waste cellulose fromTetra Pak packing and gammaradiation on themechanical properties of cement concrete.Concrete specimens were elaborated with waste cellulose at concentrations of 3, 5, and 7 wt% and irradiated at 200 , 250 , and 300 kGy of gamma dose. The results show highest improvement on the mechanical properties for concrete with 3 wt% of waste cellulose and irradiated at 300 kGy; such improvements were related with the surface morphology of fracture zones of cement concrete observed by SEM microscopy

    Facile solventless synthesis of a nylon-6,6/silver nanoparticles composite and its XPS study

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    SINTESIS DE NANOPARTICULASSilver nanoparticles were synthesized and supported on thin nylon membranes by means of a simple method of impregnation and chemical reduction of Ag ions at ambient conditions. Particles of less than 10nm were obtained using this methodology, in which the nylon fibers behave as constrained nanoreactors. Pores on nylon fibres along with oxygen and nitrogen from amide moieties in nylon provide effective sites for in situ reduction of silver ions and for the formation and stabilization of Ag nanoparticles. Transmission electron microscopy (TEM) analysis showed that silver nanoparticles are well dispersed throughout the nylon fibers. Furthermore, an interaction betweenUAEME
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