Evolution of surface area in a sepiolite as a function of acid and heat treatments

Abstract

Abstract The variations in surface area of a sepiolite (Toledo, Spain) after acid and heat treatments (1 n to 5 n , HNO 3 , 110°C to 900°C for 100 h) have been studied. Surface areas have been determined from N 2 adsorption isotherms at 77 K using B.E.T., Langmuir and Dubinin-Radushkevich equations. S BET values range from 65 up to 391 m 2 g −1 , the maximum value corresponding to the sample activated with 1 n HNO 3 solution and treated at 300°C. S L and S D-R values are similar, but slightly larger than the corresponding S BET values. A correlated study has been carried out with samples activated with 1 n and 2 n HNO 3 solutions and heat treated at 110, 200, 300, 400 and 500°C for 10 h. S BET values of these samples are rather similar to those of the corresponding samples treated during 100 h.