Determination by reactive absorption of the rate constant of the ozone reaction with the hydroperoxide anion

Pierre-Francois Biard (1) , Thom Thi Dang , Annabelle Couvert (1)

1 ISCR - Institut des Sciences Chimiques de Rennes

The reaction rate constant between the hydroperoxide anion (HO2−) and molecular ozone was evaluated from the reactive absorption method in the range of temperature from 20 to 35 °C. This reaction is crucial in the initiation step of the ozone decomposition, especially using the peroxone process which combines ozone and hydrogen peroxide in solution. A stirred-cell operated semi-continuously was used for this purpose. A high initial concentration of tert-butanol (0.05 mol L−1) was applied to efficiently scavenge all radicals and to avoid any parasite reaction. Based on the dissolved H2O2 concentration decreasing and the outlet ozone concentration time-course, the stoichiometry of the initiation reaction was determined, with one mol of H2O2 consumed per mol of ozone transferred. The chemical conditions were thoroughly selected to reach a fast pseudo-first order absorption regime. The reaction rate constant increased from 1.91 × 106–2.40 × 106 L mol−1 s−1 at 20 °C to 5.68 × 106–7.31 × 106 L mol−1 s−1 at 35 °C.

Mots clés: rate constant; activation energy; Reactive absorption; ozone; hydrogen peroxide; initiation

Domaines: Chimie théorique et/ou physique

Pierre-Francois Biard, Thom Thi Dang, Annabelle Couvert. Determination by reactive absorption of the rate constant of the ozone reaction with the hydroperoxide anion. Chemical Engineering Research and Design, 2017, 127, pp.62-71. ⟨10.1016/j.cherd.2017.09.004⟩. ⟨hal-01652337⟩