Investigation Of Chemical Oscillatory Reaction Relating To Chlorine Dioxide And Sodium Chlorite

This paper investigated the ClO2-I2-allyl acetoacetate (AAA) and NaClO2-KI-methyl acetoacetate (MAA) chemical oscillatory reaction systems by UV-vis spectrophotometric method.In the system of ClO2-I2-AAA, the induced period can not be observed at288nm and360nm without adding starch, while the reaction has an induced period at585nm by adding starch. The oscillation phenomenon is much more complex by adding starch than that observed without adding starch. We can divide the oscillation curve at585nm into two parts. In the first part of the curve, the oscillation is very weak. Then the oscillation strengthens suddenly in the second part of the curve. The number of oscillations increases, and the period of oscillations decreases, as the initial concentration of CIO2increases or the initial concentration of I2increases. The period of oscillations and amplitude increase, and the number of oscillations decreases, as the initial concentration of allyl acetoacetate increases. The number of oscillations decreases, and amplitude increases, as the pH value of the solution increases. Both the induction period and the oscillation period decrease with increasing of reaction temperature. The oscillation reaction can be accelerated by increasing reaction temperature. The apparent activation energy in terms of the oscillation period, which was calculated according to Arrhenius equation, is relatively small. The equations for the triiodide ion reaction rate changing with reaction time and the initial concentrations in the oscillation stage were obtained by differentiating and curve fitting of the oscillatory curves which were got in the experiments. The equations of the amplitude and the period of oscillation changing with initial concentrations of various substances were also obtained.In the system of NaClO2-KI-MAA, the oscillatory reaction at289nm,350nm, and469nm by adding starch were studied, the induced period can be observed obviously at the three wavelengths, and the induced time can last for about40seconds. The period of oscillations and the amplitude increase, as the initial concentration of KI. The period of oscillations and the amplitude decrease, as the initial concentration of H2SO4increases or the initial concentration of NaC102increases. The period of oscillations and the amplitude decrease, as the initial concentrations of NaClO2and KI increase at the same time by keeping the ratio of NaClO2to KI concentration constant. Both the induction period and the oscillation period decrease with increasing of reaction temperature. The oscillation life was shortened by increasing reaction temperature. The apparent activation energies in terms of the induction period and the oscillation period, which were calculated according to Arrhenius equation, are relatively small. The equations for the triiodide ion reaction rate changing with reaction time and the initial concentrations in the oscillation stage were obtained by differentiating and curve fitting of the oscillatory curves which were got in the experiments. The equations of the amplitude and the period of oscillation changing with initial concentrations of various substances were also obtained.