A jacketed stirred-cell reactor, operated semi-continuously, was used to assess the kinetics of fast ozonation reactions by reactive absorption. The method was applied to the direct ozone reaction with resorcinol. A high resorcinol concentration was used to reach a steady state and to neglect the byproducts accumulation. Thus, the mass-transfer rate, and consecutively the reaction rate, were deduced from the ozone mass balance in the gas phase. The gas-phase and liquid-phase mass-transfer coefficients were previously measured directly through the ozone absorption in appropriated conditions. The results emphasized the high sensitivity of the reaction rate constant to the ozone physicochemical properties, especially its solubility, which is controversial in the literature. Therefore, several correlations used to calculate the ozone solubility in water were considered to calculate the second-order reaction rate constant, which varied from 3.57-4.68 10 5 L mol -1 s -1 at 20°C to 9.50-12.2 10 5 L mol -1 s -1 at 35°C. The activation energy was in the range 35-59 kJ mol -1 depending on the considered ozone solubility correlation. A sensitivity analysis is provided to assess the influence of the experimental conditions and ozone physicochemical properties on the model. Finally, the applicability of this method is thoroughly discussed.2

An innovative implementation of the O 3 /H 2 O 2 advanced oxidation process was proposed to intensify the hydroxyl radical generation. Natural or drinking waters, containing atrazine as a probe compound, were spiked with H 2 O 2 and further continuously mixed to a pre-ozonated solution in a homogeneous tubular reactor filled with static mixers. Hydraulic residence times in the range 10 s-140 s were set at different sampling ports. The experimental results confirmed a very high ozone decomposition rate, concomitant with a high hydroxyl radical exposure (R ct in the range from 10-7 to 10-6), especially during the initial ozone decomposition phase (between 10 and 20 s). Equimolar initial concentrations of hydrogen peroxide and ozone were optimal to maximize the hydroxyl radical generation and to minimize their relative consumptions. The influence of the water matrix on the ozone decomposition and the hydroxyl radical generation was limited. This study is a proof of concept that using a homogeneous tubular reactor would be more effective than a gas-liquid reactor to apply the peroxone process.