Thermal analysis of sepiolite and palygorskite treated with butylamine

Abstract

Abstract The thermal behaviour of sepiolite and palygorskite treated with butylamine was investigated by DTA, TG and EGA-MS under a flow of air and N 2 . It was shown that the amine was adsorbed by the clays, penetrating into the pores and replacing zeolitic and bound water. The presence of amine in the pores shifted the dehydroxylation peak to temperatures higher than for the untreated clays. Under N 2 the thermal desorption of the amine from sepiolite was observed at 175, 275 and 525°C, and from palygorskite at 170 and 270°C. In addition to desorption, reactions of pyrolysis and condensation to charcoal were detected by the evolution of NH 3 , CH 4 or H 2 , respectively. In air, oxidation of the organic matter led to the appearance of exothermic peaks, the temperatures of the most intense peaks being determined by the rate of C oxidation, but the shape of the DTA curves and the temperatures of exothermic shoulders were determined by the rate at which H from the organic molecules combined with O from the air.