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ABSTRACT
Development of an efficient conversion technique of O3 to active oxygen species (OS) with high oxidation potential under weakly acidic conditions is described herein. This technique involves the generation of HO2– as an initiator of the radical chain reaction by the addition of H2O2 or/and UV irradiation into aqueous solution during O3 fine bubble injection. Minimizing the O3 bubble diameter led to the enhanced production of OS because of the generation of HO2– with contact between O3 and OH– around the minute gas-liquid interfaces and the promoted reaction of O3 with HO2– caused by the acceleration of O3 dissolution in the O3/H2O2 or O3/UV systems. Additionally, the generation rate of OS (rOS) in the O3/H2O2/UV system was found to be greater than the summed value of rOS in the O3/H2O2 and O3/UV systems because of the direct conversion from H2O2 to OH• under UV irradiation.
Nomenclature
(CH2O2)0: initial concentration of hydrogen peroxide [mmol/L]
COS: concentration of active oxygen species [mmol/L]
CO3: concentration of residual O3 [mmol/L]
(CTBA)0: initial concentration of tert-butyl alcohol [mmol/L]
CTBA: concentration of tert-butyl alcohol [mmol/L]
dbbl: average bubble diameter [µm]
FO2: O2 flow rate based on unit volume [mmol/(L•min)]
FO3: O3 flow rate based on unit volume [mmol/(L•min)]
rOS or (rOS)exp.: generation rate of active oxygen species [µmol/(L•min)]
(rOS)sum.: summed values of the generation rate of active oxygen species [µmol/(L•min)]