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VOL. 75 (1), 25-41, 2009 MONO AND BIEXPONENTIAL IN...

The rate constant is related to the temperature according to the
equation of Eyring (33):

k = B·T·exp(-?H‡/RT)

Eq. 8 is obtained from Eq. 5 introducing:
K (van t’Hoff) in b, d, h,
k (Eyring) in e and j, grouping the constants and simplifying.

The activation parameters are:
?H01 = 3913·8.31 = 32517 J mol-1 ?H02 = -7737·8.31 = -64294 J mol-1
?H‡1 = 6215·8.31 = 51647 J mol-1 ?H‡2 = 8601·8.31 = 71474J mol-1

When temperature increases, the concentration of PQ in equilib-
rium and the apparent rate constant increase, according to Eyring and
van’t Hoff equations.

Process 1 is endothermic and 2 exothermic. The diminution of ze
when increasing the temperature can be explained admitting that
process 2 predominates on the 1. The activation energies are much
greater than the energy of viscous flow of the water. It indicates that
the process is not controlled by diffusion.

5.6. Influence of m, q, I, ?, T (Experiments 1–16)

The results of experiments 1-16 are fitted to the equation:

z = (a-b·q)·m·exp(c/T)+d·exp(e/T)·(m/(m+f))·exp(-t·(g/?)·exp(-

h/T))+j·(m/(m+k))·exp(n/T)·exp(-t·(u/?)·exp(-w/T)) Eq. 9

Its parameters, coefficient of correlation and sum of squares of
residuals are:

a=-0.1529·10-15 b=0.234·10-15 c=11595 d=2.87·109 e=-3492
f=469 g=47.5·107 h=6995 j=0.1892·10-6 k=188.3
n=7919 u=0.1042·107 w=6152 s= 1.885·107
r= 0.992

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