DiagÃnese acelerada de caulim à zeÃlita NaA para uso no abrandamento de Ãguas. / DiagÃnese sped up of kaolinm to the zeolite NaA (LTA)for use in the water softener.

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

31/03/2006

RESUMO

Zeolite NaA (LTA) has been successfully synthesized by hydrothermal route, in which kaolim was used as silicon and aluminum source. The obtained zeolite was characterized by X-ray diffraction, X-ray absorption, thermogravimetry (TG), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), infrared absorption spectroscopy (IR), luminescence and granulometry. The X-ray diffraction data refinement by Rietveld method and software DBWS9807 has made possible the confirmation of only one crystallographic phase on the synthesis process and the particle size measurements. Particle sizes vary from 48 nm to 74 nm. Zeolite A morphologic properties were observed by scanning electron microscopy analysis, in which one could observe crystals with different sizes but with the same cubic shape. Na+ ions have been replaced for NH4 +, in a simple ion exchange process. This way, zeolite A has acquired its ammoniac state. The efficiency of this process has been confirmed by infrared analysis, with the appearance of bands in 1402 cm-1 and 1450 cm-1 after ion exchange, and by acid titillation. Zeolite thermal stability, either on Na+ or NH4 + states, has been determined by thermogravimetry. Activation energies for the thermogravimetric process related to weigh loss through volatilization caused basically by water and ammonia liberation from zeolite surface, were from 71,7 kJ.mol-1 to 205,7 kJ.mol-1. Luminescence analysis has indicated that Eu3+, used as probe, is not located in a symmetric center and the sites in which the abovementioned ion is located is not homogeneous. The particle size obtained from granulometric analysis was around 10 m, what indicates agglomerations formed by zeolite crystals. According to calcium removal analyses by zeolite A, it appears as na excellent water softener and as a potential substitute for polyphosphates, frequently used in detergents.

ASSUNTO(S)

ciencia da computacao zeÃlita a caulim metacaulim abrandamento de Ãgua. zeolite a kaolim metakaolin, water softener.

ACESSO AO ARTIGO

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