Environment
Acceleration of Bromine Oxyacid Generation and Organic Compound Decomposition by O3 Fine Bubble Injection into an Aqueous Solution Containing Bromide Ions
2020 Volume 53 Issue 11 Pages 722-728
Details
2020 Volume 53 Issue 11 Pages 722-728
To achieve the rapid decomposition of refractory organic compounds for water purification, an effective technique for the generation of bromine oxyacids by O3 fine bubble injection and bromide addition was developed. When O3 bubbles are micronized in the liquid phase, the absorption of O3 is accelerated, and OH· generation is promoted because of the increased contact probability between the dissolved O3 and accumulated OH− at the minute gas–liquid interface. Additionally, when O3 fine bubbles are supplied into a liquid phase containing Br−, further improvement in the oxidation potential of the liquid phase can be expected because of the increased HOBr/BrO− generation with OH· generation. At 298 K, O3 bubbles with an average diameter (dbbl) of 50 or 2000 µm were supplied into NaBr aqueous solutions with different initial NaBr concentrations ((CNaBr)0). The rate of generation of total oxygen species and the constant value of concentration of total oxygen species (C*OS) increased with the acceleration of the bromine oxyacid generation, induced by the decrease in dbbl and the increase in (CNaBr)0. Furthermore, the decomposition of tert-butyl alcohol (TBA) by O3 fine bubble injection at various (CNaBr)0 values was carried out. Consequently, the rate constant of TBA decomposition showed a maximum value at C*OS of 0.54 mmol/L because of the conversion of HOBr/BrO− with a high oxidation potential to BrO3− with a low oxidation potential, caused by the excess oxidation of Br−. Hence, the generation of HOBr/BrO− with O3 fine bubble injection and bromide addition is effective for achieving enhanced decomposition of refractory organic compounds.
