Ozone+Hydrogen Peroxide(O3/H2O2) – (Peroxone)
Addition of hydrogen peroxide to ozone can initiate the decomposition cycle of ozone, resulting in the formation of OH radicals:
H2O2 –>HO2 – + H+
HO2– + O3 –> HO2 . + O3–
The reaction continues along the indirect pathway described above and OH radicals are produced. The combination of different reaction steps shows that two ozone molecules produce two OH radicals:
2O3 + H2O2 → 2.OH + 3O2
In some studies, the pesticide named atrazine showed better degradation in water treated with ozone–hydrogen peroxide combination as compared to ozone alone. The optimum H2O2 /O3 mass ratio ranges from 0.35 to 0.45. The performance of the process depends on the ozone dose, contact time, and alkalinity of water. In another study, the best performance was achieved when H2O2 was added after the oxidation of highly reactive substances with ozone alone.
The implementation of a radical system makes oxidation of refractory molecules possible: it allows getting full advantage of selective molecular ozone reactions before converting the process to non-selective free radical attack. Hydrogen peroxide is a relatively inexpensive, readily available chemical oxidant. It is produced by electrolysis of ammonium bisulphate or by oxidation of alkyl hydroanthraquinones