98% sodium tungstate dihydrate may be studied by TG-DTG technology to know its dehydration process. And the non-isothermal kinetic data of the dehydration process is analyzed using the thermal analysis kinetic data processing method proposed by Malek et al.
Processing Methods of Kinetic Data
Malek et al. proposed a relatively complete set of kinetic data processing methods. The steps are as follows:
1. Activation energy E was calculated using Ozawa method and Kissiger method among the multiple scanning rate method.
2. Determine kinetic mode f(α). Substitute the experimental data into the following two definition dings Y(α) and Z(α):
Y(α)=(dα/dt)ex (1)
Z(α)=π(x)(dα/dt)T/β (2)
According to the shape of the Y(α) curve and αm at its maximum, combining the αP at the peak in the TG-DTG curve and the αP∞ value at the maximum, the f(α) can be determined.
3. Calculate kinetic power exponent n (and m) according to the determined dynamic model.
4. Calculate pre-exponential factor A by the following formula on basis of activation energy value and kinetic model.
A=-βxp exp(xp)/[TPf′(αp)] (3)
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