Obtención, caracterización y empleo como sorbente del silicato de magnesio amorfo hidratado
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Fecha
2009-06-25
Autores
González Rodríguez, Lisdelys
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Universidad Central "Marta Abreu" de las Villas
Resumen
En este trabajo se desarrolla la síntesis del compuesto silicato de magnesio amorfo hidratado, sólido poroso, de color blanco, térmicamente estable. A este producto inorgánico se le efectuó un parcial análisis químico, junto al análisis de algunos de sus parámetros físicos para su caracterización y definición. Los parámetros físicos medidos son: densidad real, densidad aparente, densidad aparente por aprisionamiento, porosidad, compresibilidad, y velocidad de flujo. También se calculan los valores de calor de disociación, difusividad efectiva y teórica, producto iónico, superficie específica, radio y volumen medio de poro. Se utiliza un amplio espectro de técnicas de análisis, tales como, la espectroscopía de absorción atómica, la difracción de Rayos-X, los análisis térmicos, análisis infrarrojo cualitativo, y espectrofotometría UV-VIS.
Se realiza el estudio cinético y termodinámico de adsorción en silicato de magnesio de algunos iones de la primera serie de transición. Como modelos utilizados se encuentra, el modelo cinético de pseudo segundo y pseudo primer orden, el modelo de Elovich, y el modelo cinético de difusión intrapartícula. Ajustándose la cinética de adsorción de los iones cobre (II), níquel (II), hierro (II) y manganeso (II) a un modelo de pseudo segundo orden, mientras el cobalto (II) se ajusta al modelo de Elovich, y el zinc (II) muestra un comportamiento cinético de pseudo primer orden además de evidenciar la difusión intrapartícula. La termodinámica fue ejecutada por espectroscopía de absorción atómica. Los modelos manejados son: Langmuir, BET, Toth, Freundlich, Dubinin-Radushkevich, Langmuir-Freundlich, Redlich, Radke-Prausnitz, Combinado y Tempkin. La adsorción de hierro (II) se puede ajustar al modelo de Langmuir, zinc (II), níquel (II), cobre (II) y cobalto (II) al modelo de Toth, y al modelo termodinámico de Radke-Prausnitz el manganeso(II).
In this work the synthesis of a silicate from hydrated amorphous magnesium is carried out. This is a thermally stable white and porous solid. In order to characterize this inorganic product a partial chemical analysis, followed by the analysis of some of its physical parameters were carried out. The following physical parameters were determined: real density, bulk and apparent density, porosity, compressibility and flow rate. The values of dissociation heat, effective and theoretical diffusion, ionic product, specific surface, ratio and half volume of pore were also calculated. A wide range of analytical techniques, such as, atomic absorption spectroscopy, X-Ray diffraction, thermal analyses, qualitative infrared analysis and UV-Vis spectroscopy were used. A kinetic and thermodynamic study of the adsorption on magnesium silicate of some ions of the first transition series is carried out. The kinetic pattern of pseudo second and pseudo first order, the Elovich pattern and the kinetic pattern of intraparticles diffusion were used in this study. The kinetics of adsorption of the ions copper (II), nickel (II), iron (II) and manganese (II) fit to pseudo second order model. Cobalt (II) follows a Elovich whereas zinc (II) follows a kinetic behaviour of pseudo first order and also shows intraparticle diffusion. Thermodynamic studies were executed by atomic absorption spectroscopy. Used models were: Langmuir, BET, Toth, Freundlich, Dubinin-Radushkevich, Langmuir-Freundlich, Redlich, Radke-Prausnitz, Cocktail and Tempkin. The adsorption of copper (II) and iron (II) followsa Langmuir pattern. Zinc (II), nickel (II) and cobalt (II) follows a Toth pattern and manganese to the thermodynamic pattern of Radke-Prausnitz (II).
In this work the synthesis of a silicate from hydrated amorphous magnesium is carried out. This is a thermally stable white and porous solid. In order to characterize this inorganic product a partial chemical analysis, followed by the analysis of some of its physical parameters were carried out. The following physical parameters were determined: real density, bulk and apparent density, porosity, compressibility and flow rate. The values of dissociation heat, effective and theoretical diffusion, ionic product, specific surface, ratio and half volume of pore were also calculated. A wide range of analytical techniques, such as, atomic absorption spectroscopy, X-Ray diffraction, thermal analyses, qualitative infrared analysis and UV-Vis spectroscopy were used. A kinetic and thermodynamic study of the adsorption on magnesium silicate of some ions of the first transition series is carried out. The kinetic pattern of pseudo second and pseudo first order, the Elovich pattern and the kinetic pattern of intraparticles diffusion were used in this study. The kinetics of adsorption of the ions copper (II), nickel (II), iron (II) and manganese (II) fit to pseudo second order model. Cobalt (II) follows a Elovich whereas zinc (II) follows a kinetic behaviour of pseudo first order and also shows intraparticle diffusion. Thermodynamic studies were executed by atomic absorption spectroscopy. Used models were: Langmuir, BET, Toth, Freundlich, Dubinin-Radushkevich, Langmuir-Freundlich, Redlich, Radke-Prausnitz, Cocktail and Tempkin. The adsorption of copper (II) and iron (II) followsa Langmuir pattern. Zinc (II), nickel (II) and cobalt (II) follows a Toth pattern and manganese to the thermodynamic pattern of Radke-Prausnitz (II).
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Silicatos de Magnesio/aislamiento & purificación, Magnesium Silicates, Espectrofotometría, Spectrophotometry, Espectrofotometría Ultravioleta