Uncatalyzed oxidation of aqueous sodium sulfite and its ability to simulate bacterial respiration

Kinetics of the uncatalyzed oxidation of sodium sulfite in dilute, aqueous solution is investigated by measuring oxygen transfer rates to both well-stirred and quiescent pools of solution under pseudo-steady-state conditions with respect to dissolved oxygen.Oxygen partial pressures ranging from 0.08 to 042 atm and sulfite concentrations varying between 0.002 and 0.04M are studied with well-stirred experiments.Results clearly indicate that the reaction orders are zero and 0.65 with respect to dissolved oxygen and sul- fite concentrations, respectively, and the reaction rate constant is 5.77 x 10-5M0.35/s.With this rate expression, film theory is used to predict oxygen transfer rates to quiescent pools of sulfite solution.The excellent agreement between these predictions and our oxygen flux measurements further confirms the validity of our kinetic expression.Because it is zero order in oxygen and its rate is comparable to the respiration kinetics of microorganisms, the uncatalyzed oxidation of dilute sulfite solutions is an ideal model for simulating t h e effect of microbial respiration on the interphase transfer of oxygen to fermentation broths.