TY - JOUR
T1 - Kinetics and mechanism of dehydration of natrolite and its potassium exchanged form
AU - Otsuka, R.
AU - Yamazaki, A.
AU - Kato, K.
N1 - Funding Information:
The authors thank Drs. A. Kato and S. Matsubara, National Science Museum, for providing the natrolite sample. This study was partly supported by the Grant in Aid for the Scientific Research of the Ministry of Education, Japan (C-01550499).
PY - 1991/5/10
Y1 - 1991/5/10
N2 - A kinetic analysis was done of the dehydration in natrolite and its corresponding potassium exchanged form. Kinetic evaluation of the thermogravimetric data based on Ozawa's methods yielded the following results: the activation energy is 126.83 kJ mol-1 for natrolite and 74.01 kJ mol-1 for the potassium form, the frequency factor is 1.92 × 109 s-1 for natrolite and 3.31 ×107 s-1 for the potassium form, and the dehydration follows zero-order kinetics in natrolite and first-order kinetics in the potassium form. Considering the crystal structures of the hydrated and dehydrated phases of natrolite and its potassium form, together with the results of the kinetic analysis, it is suggested that the dehydration in natrolite proceeds at a constant rate in one direction parallel to the c axis, while in the potassium exchange form the dehydration is instantly completed in each particle and then proceeds particle by particle.
AB - A kinetic analysis was done of the dehydration in natrolite and its corresponding potassium exchanged form. Kinetic evaluation of the thermogravimetric data based on Ozawa's methods yielded the following results: the activation energy is 126.83 kJ mol-1 for natrolite and 74.01 kJ mol-1 for the potassium form, the frequency factor is 1.92 × 109 s-1 for natrolite and 3.31 ×107 s-1 for the potassium form, and the dehydration follows zero-order kinetics in natrolite and first-order kinetics in the potassium form. Considering the crystal structures of the hydrated and dehydrated phases of natrolite and its potassium form, together with the results of the kinetic analysis, it is suggested that the dehydration in natrolite proceeds at a constant rate in one direction parallel to the c axis, while in the potassium exchange form the dehydration is instantly completed in each particle and then proceeds particle by particle.
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U2 - 10.1016/0040-6031(91)80411-B
DO - 10.1016/0040-6031(91)80411-B
M3 - Article
AN - SCOPUS:33747284740
VL - 181
SP - 45
EP - 56
JO - Thermochimica Acta
JF - Thermochimica Acta
SN - 0040-6031
IS - C
ER -