Kinetic Investigation of the Autocatalytic Reaction between Potassium Permanganate and Hydrogen Peroxide with Soft-modeling Methods

The complex autocatalytic reaction between potassium permanganate (KMnO4) and hydrogen peroxide (H2O2) was studied by online UV-Vis spectra methods. The kinetic profiles of the absorptive components, including KMnO4 and two intermediates, were obtained by resolving the spectra-kinetic matrix with iterative target transformation factor analysis (ITTFA). But for the product Mn(II), which is not absorptive in the monitoring wavelength range, this was not applicable. Therefore, local mass balance region (LMBR) technique was proposed to get all of the scaled profiles, especially the non-absorptive components. Influences of various reaction conditions, such as concentrations of H2O2 and sulfuric acid (H2SO4) and reaction temperatures, were also investigated. Contrary to most other reactions, when initial concentrations of hydrogen peroxide ([H2O2](0)) are largely excessive ([H2O2](0)/[KMnO4](0) > 40), higher [H2O2](0) will decrease the degradation rate, while the higher temperature makes the reaction go much slower.