Study of ClO2 generation reaction via experimental data of aqueous mixed electrolyte solutions: HClO4–NaCLO3–H2O and HCLO4–NaCl–H2O

A new model for mixtures (two and more solutes) of aqueous electrolyte solutions was found to be as accurate as other models, or more accurate, in prediction of new experimental results of the ternary systems HClO4–NaClO3–H2O and HClO4–NaCl–H2O. The water activity values are then used to study the mechanism of the chloride–chlorate reaction, generating chlorine dioxide: 2H+ + ClO−3 + Cl− ClO2 + 1/2Cl2 + H2O Spectrophotometric measurements of the production rate of ClO2 have confirmed that the intermediary species in the proposed equilibrium H+(mH2O) H+(m-n)H2O + nH2O Is actually H(H20)+m-n. The final kinetic expression for the reaction rate of chlorine dioxide generation, used in pulp bleaching, is then derived to explain the high order with respect to acid concentration.