Experimental and kinetics of the oxidation of ammonium sulfite by hydrogen peroxide in ammonia flue gas desulfurization

The oxidation of ammonium sulfite obtained from ammonia-based flue gas desulfurization by hydrogen peroxide in aqueous solutions was studied using a stirred reactor. An experimental study of the kinetic parameters of the oxidation process was investigated in the pH of 4.2-5.2 at 25-50 degrees C. r = k(3)[H+ ][HSO3- ][H2O2] is valid at sulfite concentrations of 10(-4) mol/L for the pH range 4.2-5.2. At 298K and pH of 5.0, third-order rate constant k(3) was found to be (6.9 +/- 0.21)x10(7) (mol/L)(-2)s(-1). When the concentration of sulfite is 0.01 mol/L, the reaction first-order with respect to sulfite and hydrogen peroxide, and the second-order reaction rate constant at pH of 4.2-5.4 islg k(2) = - 1.0135pH + 7.4862. Activation energy of E-a = 32.26 kJ/moL. Kinetic data were compared with previous studies. A semi-empirical formula can express the effect of ionic strength on k(3). The kinetic data of ammonium sulfite oxidation with hydrogen peroxide have potential applications in the wet ammonia desulfurization process.