Calcium bisulfite oxidation rate in the wet limestone-gypsum flue gas desulfurization process

In this paper oxidation of calcium bisulfite in aqueous solutions was studi ed, in connection with the limestone-gypsum flue gas desulfurization proces s. Experimental measurements of the oxidation rate were carried out in a la boratory scale stirred reactor with continuous feeding of both gas and liqu id phase. A calcium bisulfite clear solution was used as liquid phase, and pure oxygen or mixtures of oxygen and nitrogen were used as gas phase. Expe riments were carried out at T = 45 degrees C varying the composition of the liquid phase and the oxygen partial pressure. Manganous sulfate was used a s catalyst. The analysis of the experimental results showed that the kineti cs of bisulfite oxidation in the presence of MnSO4 follow a parallel reacti on mechanism, in which the overall reaction rate can be calculated as the s um between the uncatalyzed rate (3/2 order in bisulfite ion) and the cataly zed reaction rate (first order in manganous ion).