Dynamics Study Of Hydrogen Peroxide Decomposition

As its environment-friendly features, hydrogen peroxide is widely used in the ECF, TCF bleaching of chemical pulp and mechanical pulp. However, the hydrogen peroxide would be decomposed by some impurities exists in the pulp, such as bacteria, affecting the efficiency of bleaching. Among all the factors which cause the decomposition, manganese ions are of the most significant catalytic role. This study focused on the dynamics of hydrogen peroxide decomposition by Mn (â…¡).A pale yellow complex compound would form through the reaction of hydrogen peroxide and ammonium molybdate under an acid condition. According to this, an ultraviolet spectrophotometer could be sued to measure the content of hydrogen peroxide. In the study a single-factor test method was used to discuss how the pH, content of hydrogen peroxide, content of Mn (â…¡) and temperature affect the decomposition of hydrogen peroxide. Research shows that hydrogen peroxide and the acid ammonium molybdate complex has an absorption in a UV range. So the absorbance of the complex at 350nm could be used to quantitative the content of hydrogen peroxide. And a isoabsorptive point at 297nm could be used through the dual-wavelength UV measurement to eliminate the influence of lignin in the residual liquid after bleaching. The UV measurement can be used for the rapid determination of hydrogen peroxide in factory.Under alkaline conditions, the OH~- act as a catalyst, the decomposition of hydrogen peroxide is a second-order reaction. The rate equation of hydrogen peroxide decomposition was:Under alkaline conditions, the decomposition of hydrogen peroxide catalyzed by Mn (â…¡) is a first-order reaction. The reaction rate above which in the alkaline conditions without Mn (â…¡).During the reaction Mn (â…¡) act as a catalyst and partly transform to be Mn (â…¢) ,which katalysis is stronger than Mn (â…¡) . The rate equation of hydrogen peroxide decomposition catalyzed by Mn (â…¡) was:The effect of temperature on the hydrogen peroxide decomposition catalyzed by Mn (â…¡) was discussed. The results showed that the increase of temperature accelerate the decomposition of hydrogen peroxide, The Arrhenius Activation Energy E_a = 75.84kJ/mol. Also, the kinetics model of decomposition of hydrogen peroxide catalyzed by Mn (â…¡) has been founded, based on the latter study, as follow:...