The kinetic
s of the activated carbon ozonation of mixture
s of three polyphenol compound
s (gallic acid, tyro
sol,and
syringic acid) in water ha
s been
studied from the application of a double mechani
sm of reaction
s toexperimental data. The
se mechani
sm
s involve direct ozone reaction
s with
starting polyphenol
s and hydroxylfree radical reaction
s with intermediate
s and end reaction product
s, mainly
saturated carboxylic acid
s (theconcentration being repre
sented with the chemical oxygen demand, COD). The direct ozone reaction mechani
smdevelop
s during the initial period (15-60 min) where polyphenol
s are removed. The kinetic regime of theproce
ss wa
s fa
st of p
seudo fir
st order, and at 25
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s/entitie
s/deg.gif">C and pH 5 the direct rate con
stant
s of the reaction
s betweenozone and gallic acid,
syringic acid, and tyro
sol were determined from different kinetic method
s. Oncepolyphenol
s di
sappear and
saturated carboxylic acid
s (end reaction product
s) are pre
sent, the removal ofthe
se compound
s goe
s through hydroxyl free radical oxidation. Thi
s second mechani
sm involve
s the reactionof ozone and the organic matter, through hydrogen peroxide formation, both in bulk water and on the carbon
surface, a
s the initiating
step of hydroxyl radical formation. In the ab
sence of activated carbon, the activationenergy of the bulk water ozone-organic matter reaction wa
s found to be 36.3 ± 4.5 kcal·mol
-1. In thepre
sence of activated carbon, at the condition
s here applied in addition to bulk water chemical reaction, theproce
ss depend
s on ma
ss-tran
sfer re
si
stance
s, and the value
s of the volumetric liquid-
side and individualliquid-
solid external ma
ss-tran
sfer coefficient
s were found to be 0.71 ± 0.05 min
-1 and 1.19 ± 0.10 × 10
-3m·min
-1, re
spectively.