Preparación de carbones activados a partir de maderas tropicales para la eliminación de metales pesados
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Fecha
2006-06-25
Autores
Débora Rodríguez, Yosdeivy
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Universidad Central "Marta Abreu" de las Villas
Resumen
En este trabajo, se estudió la factibilidad de la eliminación de los iones metálicos pesados Cd2+, Co2+, Cu2+,Fe3+, Mn2+ y Zn2+, mediante adsorción con carbones activados obtenidos por activación “física” de dos maderas tropicales (anoncillo y brasilete) con vapor de agua. Se estudió fundamentalmente la influencia de las condiciones de operación empleadas: temperatura (600-800°C) y tiempo (de 60 a 120 min.) sobre las propiedades de los diferentes carbones, haciendo énfasis en las indicadoras del poder adsorbente: índices de azul de metileno y de yodo. A todas las variables respuesta de interés se les realizó el correspondiente análisis estadístico que permitió definir la influencia de las variables independientes temperatura y tiempo sobre éstas. Se obtuvo que tanto el precursor como el agente activante estudiado resultaron adecuados para la preparación de carbones activados con un elevadísima capacidad de adsorción; las mejores condiciones para preparar los adsorbentes deseados se correspondían con las de los experimentos 6 para el anoncillo y 8 para el brasilete, productos que eliminan prácticamente el 100% de los iones presentes en solución acuosa. Se determinaron los parámetros cinéticos característicos de los procesos de pirólisis y activación, empleando un modelo simple, el cual brindó resultados satisfactorios. Por último se realizó la caracterización fásica de las diferentes muestras, la que posibilitó establecer correlaciones útiles entre la cristalinidad de los productos sintetizados y las pérdidas en masa que tenía lugar durante los procesos de termoconversión estudiados.
In this work, the feasibility of the elimination of heavy metallic ions Cd2+, Co2+, Cu2+,Fe3+, Mn2+ and Zn2+ is studied by adsorption with activated carbon obtained by “physical” activation of two tropical woods (anoncillo and brasilete) with steam water. The influence of the operation conditions used: temperature (from 600 to 800°C) and time (from 60 to 120 min.) on the properties of the different carbons was studied, making emphasis in those that are indicative of the adsorbent power: methylene blue and iodine indexes. For all the answer variable of interest the corresponding statistical analysis to define the influence of the independent variables temperature and time on these were carried out. It was obtained that the precursor such as the activating agent studied were appropriate for the preparation of activated carbons with a very high adsorption capacity; the best conditions to prepare the adsorbents belonged with those of the experiments 6 for anoncillo and 8 for brasilete, products that remove practically 100% of those ions present in watery solution. The kinetic parameters that characterize the pyrolysys and activation process were determined, using a single model, which gave satisfactory results. Finally, the phasical characterizations of the different samples were did, that allowed obtain useful correlations between the cristalinity of the synthesized products and the mass decrease that took place during the thermal conversion process.
In this work, the feasibility of the elimination of heavy metallic ions Cd2+, Co2+, Cu2+,Fe3+, Mn2+ and Zn2+ is studied by adsorption with activated carbon obtained by “physical” activation of two tropical woods (anoncillo and brasilete) with steam water. The influence of the operation conditions used: temperature (from 600 to 800°C) and time (from 60 to 120 min.) on the properties of the different carbons was studied, making emphasis in those that are indicative of the adsorbent power: methylene blue and iodine indexes. For all the answer variable of interest the corresponding statistical analysis to define the influence of the independent variables temperature and time on these were carried out. It was obtained that the precursor such as the activating agent studied were appropriate for the preparation of activated carbons with a very high adsorption capacity; the best conditions to prepare the adsorbents belonged with those of the experiments 6 for anoncillo and 8 for brasilete, products that remove practically 100% of those ions present in watery solution. The kinetic parameters that characterize the pyrolysys and activation process were determined, using a single model, which gave satisfactory results. Finally, the phasical characterizations of the different samples were did, that allowed obtain useful correlations between the cristalinity of the synthesized products and the mass decrease that took place during the thermal conversion process.
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Palabras clave
Carbones Activados, Metales Pesados, Metals, Heavy