UV-induced Decomposition of Ozone and Hydrogen Peroxide in the Aqueous Phase at pH 2–7

Abstract

The photolysis of ozone and formation of hydrogen peroxide were investigated in solution of pH 2–7, in a 200 cm³ photoreactor in the incident photon flow range 9.6 x 10⁻⁸ - 4.2 x 10⁻⁷ einstein s⁻¹. The quantum yield of the primary photochemical reactions was measured in a direct way by suppressing the secondary radical reactions. The determined quantum yields of the photo-decompositions of ozone and hydrogen peroxide were 0.42 ± 0.042 ± 0.04 and 0.49 ± 0.04, respectively.

A correct mathematical treatment is given for calculation of the light absorption of the individual components of a multi-absorbent reaction mixture.

On the basis of the literature data and die present results, a probable chemical and reaction kinetic model was proposed to characterize the investigated reaction systems. Reaction kinetic simulations demonstrated that the model predicts a good fit to the measured data with the preferred literature rate constants, except that for the HO₃ radical decomposition reaction. A reasonable reduction of this rate coefficient value is in accordance with the latest published results.

Keywords:

• Ozone
• UV Photolysis
• Hydrogen Peroxide
• Reaction Kinetic Simulation;
• Quantum Yield