Abstract
Ozonation of cornstarch at pH 13 was performed using a semi-batch
reactor to analyse the influence of a continuous ozone-oxygen gas flow
(40 NL/h) at different ozone concentrations (0-42.30 g/Nm3) and
temperatures (20-60ºC). A pseudofirst-order kinetic model was proposed
to elucidate the reaction mechanisms associated with ozone at high pH
conditions. The radical concentration remains constant and proportional
to the ozone continuous dose, being a non-limiting factor independent of
temperature (activation energy 14.2-14.5 KJ/mol). The oxidation kinetic
of starch was studied monitoring the Chemical Oxygen Demand, finding a
reduction in ozone concentration when both temperature and time
increased (activation energy 8.1 KJ/mol). Therefore, the model proposed
for the starch ozonation at high alkaline solutions provides a better
understanding of the oxidation processes of common product additives
such as starch, also making it possible to determine the environmental
impact of such solutions by Chemical Oxygen Demand measurement.