Mechanism of Isothermal Reaction in Solid State

Based on the standard equation for the analysis of nucleation and growth processes, the kinetics of isothermal solid-state reactions can be represented by the following equation [15]  

Designation Functional form Rate-controlling process 

[1-(1 - ) ] = Af Three-d i mensional diffusion, spherical symmetry, Jander equation 

When ln[-ln(l - a)] is plotted against In t, if the range of a is limited to 0.15-0.50, the kinetic data give a linear plot with slope m. Dehydroxylation of kaolinite was carried using 91 mg of sample at 427 °C in vacuo, and f(, 5 = 97 min was obtained. A linear plot with a slope (m) of 0.56 was produced, indicating a diffusion-controlled reaction. It is attributable to either D2 or D4 as shown in Table 3.6. 

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