Chlorine Dioxide–Iodine–Acetylacetone Oscillation Reaction Investigated by UV–Vis and Online FTIR Spectrophotometric Methods

In order to study the chemical oscillatory behavior and mechanism of a new chlorine dioxide–iodine–acetylacetone reaction system, a series of experiments were carried out by using UV–Vis and online FTIR spectrophotometric methods. The initial concentrations of acetylacetone, chlorine dioxide, iodine, sulfuric acid, and the pH value have considerable influence on the oscillations observed at wavelength of 350 nm for the starch–triiodide ion complex (QI3-\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{QI}{_{3}^-}}$$\end{document}). There is a pre-oscillatory or induction stage, the amplitude and the number of oscillations are associated with the initial concentration of reactants. Equations were obtained for the starch–triiodide ion complex (QI3-\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{QI}{_{3}^-}}$$\end{document}) reaction rate change with reaction time and the initial concentrations in the oscillation stage. The oscillation reaction can be accelerated by increasing the reaction temperature. The apparent activation energies at the induction stage and the oscillation stage are 45.64 and 12.39 kJ·mol−1, respectively. The intermediates were detected by the online FTIR analysis. Based upon the experimental data in this work and in the literature, a plausible reaction mechanism was proposed for the oscillation reaction.