Kinetics of chlorate formation during ozonation of aqueous chloride solutions

Mechanism and Kinetic Model of Chlorate and Perchlorate Formation during Ozonation of Aqueous Chloride Solutions

“…the apparent rate constant being equal to 1 × 10 4 s −1 . 56 It should be noted that other possible chemical equations of Cl 2 O 2 hydrolysis reaction are in poor agreement with the experimental data 14,16 on the kinetics of chlorate generation during the ozonation of aqueous chlorides. Indeed, the assumption that the products of Cl 2 O 2 hydrolysis are HOCl and ClO 2 − always leads in this work to an increase in the discrepancy between the calculated and experimental rates of chlorate formation.…”

“…The equilibrium constants (acid dissociation constants and Henry's constants) conform to the ionic strength of 1 M, which is consistent with the experimental conditions. 14,16 The value of the true Henry's law constant of ozone, H O3 = 0.18, is taken from ref 42. Below, we describe the kinetic characteristics of key steps in the set of reactions.…”

“…73 The calculation results were compared with the following experimental data: the dependencies of chlorate formation rate on pH and ozone and chloride ion concentrations; 16 the dependency of ozone solubility coefficient on pH; 14 and the values of perchlorate formation rates during the ozonation of chloride solutions under various conditions. 15,18 In most of the calculation runs, the parameters of the kinetic equations reflected the experimental conditions in previous works 14,16 and took the following values: temperature, 20 °C; ionic strength and chloride ion concentration in the reaction solution, 1 M; ozone concentration in the gas flow at the entrance to the reactor C°(O 3 ) = 95 g/m 3 ; k L a = 0.1 s −1 ; 74 V liq = 0.25 L; V gas = 0.055•V liq ; and υ = 21 L/h = 5.83 × 10 −3 L/s. When modeling the formation of perchlorate, the parameters of the equations corresponded as far as possible to the experimental conditions.…”

“…The formation of chlorate during the reaction of ozone with chloride ion in aqueous solutions was discovered in previous works. 14,15 The kinetics of this process was investigated in ref 16, its important and characteristic feature being the maximum of chlorate formation rate at pH 10 in 1 M NaCl solution. The formation of small amounts of perchlorate during the interaction of O 3 with Cl − under various conditions was demonstrated in many publications.…”

“…• ) = −2, appears in the literature; 70 however, its use in the model leads to the growth of discrepancies between the calculation results and experimental kinetic laws. 14,16 It is known that fast reactions in solutions are diffusioncontrolled. 71 In our model, we used the value k D = 1 × 10 10 L mol −1 s −1 as an estimate of the rate constant of such reactions between electrically neutral particles.…”