Original scientific paper

Kinetic Analysis of Crystal Growth of Zeolite A

Sanja Bosnar ; Ruđer Bošković Intitute, Laboratory for the Synthesis of New Materials, Division of Material Chemistry, P.O. Box 180, Zagreb, Croatia
Boris Subotić orcid.org/0000-0002-3589-7845 ; Ruđer Bošković Intitute, Laboratory for the Synthesis of New Materials, Division of Material Chemistry, P.O. Box 180, Zagreb, Croatia

Abstract

Changes of the concentrations of aluminium, c_Al, and of Silicon, c_Si, in the liquid phase as well as of the dimension, L_m, of the largest crystals were measured during crystallization of zeolite A from the amorphous aluminosilicate precursor (1.03 Na₂O ⋅ Al₂O₃ ⋅ 2.38 SiO₂ ⋅ 1.66 H₂O) dispersed in alkaline Solutions (1.2 or 1.4 M NaOH solution) containing or not containing dissolved Al₂O₃ and/or SiO₂ of appropriate concentrations. Analysis of the relationship between the concentration factors f(c) = f(c_Al,c_Si) relevant to different growth models and the growth rate of zeolite A crystals have shown that the growth is governed by the reaction of monomeric and/or low-molecular aluminate, silicate and aluminosilicate anions from the liquid phase on the surfaces of growing zeolite crystals, and hence that the kinetics of the growth rate of zeolite A crystals may be expressed as: dL/dt_c = k_g[c_Al - c_Al(eq)][c_Si - c_Si(eq)] = k_gf(c) , where t_c is the time of crystallization, c_Al(eq) and c_Si(eq) are the aluminium and Silicon concentrations in the liquid phase, corresponding to the solubility of zeolite A under given crystallization conditions, and k_g is the rate constant of the linear growth of zeolite A crystals.

Keywords

zeolite A; crystallization; crystal growth; mechanism; kinetics

Hrčak ID:

127548

URI

https://hrcak.srce.hr/127548

Publication date:

1.8.2002.

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