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Activation of a sepiolite with dilute solutions of HNO3 and subsequent heat treatments: III. Development of porosity

  • F. Rodríguez-Reinoso (a1), A. Ramírez-Sáenz (a1), J. De D. López-González (a1), C. Valenzuela-Calahorro (a1) and L. Zurita-Herrera (a1)...

Abstract

Porosity development in a sepiolite from Toledo, Spain, has been studied as a function of acid (0·25, 0·50, 0·75 and 1·0 m HNO3) and subsequent heat treatments (110–400°C). Adsorption isotherms of N2 at 77 K have been analysed by f-plot, t-plot, α s-plot and the Cranston & Inkley methods. Results are compared with those obtained on products heated without previous acid activation. Experimental conditions favouring porosity development are discussed.

Résumé

On a étudié l'accroissement de la porosité d'une sépiolite de Tolède, Espagne, en fonction de traitements acides (HNO3 0·25, 0·50, 0·75 et 1·0 M) suivis de chauffage (110°–400°C). Les isothermes d'adsorption de N2 à 77 K ont été analysées selon les méthodes graphiques f, t, α s et par celle de Cranston et Inkley. On compare les résultats à ceux de produits chauffés n'ayant pas subi d'activation acide. On discute des conditions expérimentales qui favorisent l'accroissement de la porosité.

Kurzreferat

Untersucht wurde die Porositätsentwicklung eines Sepiolits aus Toledo, Spanien, in Abhängigkeit von Säure (0·25, 0·50, 0·75 und 1·0 m HNO3) und anschließender Hitzebehandlung (110–400°C). Mittels f-, t-, α s-Plot und der Cranston-u. Inkley-Methodik wurde die N2 Adsorptionskurve bei 77 K ermittelt. Diese Ergebnisse werden mit denen von erhitzten Proben ohne vorherige Säurebehandlung verglichen. Ferner werden jene experimentellen Bedingungen diskutiert, welche die Porositätsentwicklung fördern.

Resumen

Se ha estudiado la evolución de la porosidad de una sepiolita de Toledo (España) producida por la activación con disoluciones de HNO3 (0·25, 0·50, 0·75 y 1·0 m), seguida de tratamientos térmicos en el intervalo 110–400°C. Para ello, las isotermas de adsorción de N2 a 77 K se han analizado utilizando los métodos f, t, α s y el de Cranston e Inkley. Los resultados se han comparado con los obtenidos para las muestras tratadas térmicamente alas mismas temperaturas pero sin activación ácida previa. Se discuten las condiciones experimentales más favorables para el desarrollo de la porosidad de la sepiolita.

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References

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Activation of a sepiolite with dilute solutions of HNO3 and subsequent heat treatments: III. Development of porosity

  • F. Rodríguez-Reinoso (a1), A. Ramírez-Sáenz (a1), J. De D. López-González (a1), C. Valenzuela-Calahorro (a1) and L. Zurita-Herrera (a1)...

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