KINETICS AND MECHANISM OF THE REACTION BETWEEN THIOSULFATE AND CHLORINE DIOXIDE

The reaction between thiosulfate and chlorine dioxide in slightly alka line medium has been studied by stopped-flow techniques. The reaction cannot be studied under pseudo-first-order condition, thus a new appro ach based on the improved calibration and use of stopped-flow spectrop hotometers was applied. The reaction starts with irreversible formatio n of . S2O3ClO22- radical. The main path of the reaction produces tetr athionate and chlorite through the formation of light absorbing tetrat hionate radical (. S4O63-). Any of the reactant present in excess slig htly modifies the 1:1 stoichiometry, and sulfate as well as chloride i ons are also formed. A detailed mechanism based on a rigorous simultan eous fitting of the experimental data is proposed.