Influence of Air Temperature and Humidity on Dehydration Equilibria and Kinetics of Theophylline

Table 2

Dehydration rate models.

Model	Description
(A) (−ln(𝑋/𝑋cr))^1/2=𝑘(𝑡−𝑡cr) (*)	Avrami-Erofeev’s equation for solid state transition by random nucleation [2].
(B) −ln(𝑋/𝑋cr)=𝑘(𝑡−𝑡cr) (**)	classical first order chemical kinetics [2].
(C) −ln((1−1−𝑋/𝑋cr^1/2)𝜋^2/8 ) =𝑘(𝑡−𝑡cr) (***)	spatially averaged solution of 2-D Fick’s transient diffusion equation [10].

𝑋_cr=0.8𝑋₀ is the fitting start water content, 𝑋₀ is the product initial water content, and 𝑡_cr is the fitting start time.