Article

Modelado no isotérmico al equilibrio de plaguicidas en fase acuosa sobre carbón activado

Interciencia (Impact Factor: 0.28). 01/2008;
Source: OAI

ABSTRACT Se realizó el modelado no isotérmico de la adsorción de los plaguicidas en solución acuosa sobre carbón activado y el análisis de parámetros de los modelos seleccionados, utilizando tres carbones activados, uno de producción venezolana (V-100) y dos utilizados ampliamente en Europa (Chemvirom Filtrasorb 400 y carbón picatif NC90). Fueron considerados dos plaguicidas, Atrazina e Imidacloprid, y once modelos de equilibrio: Freundlich, Langmuir, Langmuir-Freundlich, Fowler-Guggenheim, Hindarso, Temkin-Frumkin, Temkin, Khan, Toth, Dubinin-Astakhov y Jaroniec-Choma. Los parámetros respectivos fueron determinados a través de la minimización de la diferencia entre la cantidad de plaguicida adsorbido experimentalmente y la calculada según el modelo, utilizando SOLVER de Microsoft EXCEL. Para discriminar los citados modelos se consideró la coherencia de resultados, el análisis de varianza de los parámetros y las hipótesis físicas que sirvieron para construir los modelos. Cuatro modelos presentaron precisión suficiente y fueron físicamente exactos: Freundlich, Langmuir-Freundlich, Fowler-Guggenheim y Dubinin-Astakhov. El análisis de parámetros de los modelos seleccionados evidenció la influencia de las características de los carbones y plaguicidas utilizados. La visualización de un fenómeno de superposición entre los modelos de Freundlich y Langmuir-Freundlich, utilizando la distribución ponderada por el número de sitios de adsorción, indica que este último representa mejor la distribución de sitios utilizados por el plaguicida en las condiciones de adsorción. Se obtuvo una regresión lineal, con buena correlación, entre el volumen de microporos y la capacidad de adsorción para la mayor parte de los modelos seleccionados.

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