Effect of Initial Substrate Concentrations and Temperature on the Oscillatory Behavior of Phloroglucinol-Based Belousov-Zhabotinsky Reaction

The present study introduces the use of phloroglucinol (1,3,5-trihydroxybenzene) as organic substrate in BZ reaction for the first time. This work has been carried out to assess the influence of initial reagent concentrations on the behavior of phloroglucinol-bromate-ferroin-based BZ reaction in a stirred batch reactor. The oscillations are followed by observing the change in redox potential. Different oscillatory parameters like induction time (t(in)), time period (t(p)), amplitude (A), frequency (v), and number of oscillations (N) show different changes with respect to changes in the initial concentrations of organic substrate, bromate and sulfuric acid, and these observations have been explained on the basis of FKN mechanism. The behavior of the aforesaid system in different aqueous acid media has been reported and it is found that sulfuric acid is the best medium for studying the system as it shows a wide oscillatory window compared to that of nitric acid. In phosphoric and perchloric acids the system does not show any oscillatory behavior. Activation parameters of the reaction have been derived by studying the reaction over a temperature range of 15 to 40 +/- 0.1 degrees C. The effect of different catalysts on the oscillatory behavior has been studied and it is found that the system gives good oscillatory behavior with ferroin and Ce(III) whereas a poor response is seen when Mn(II) and Ce(IV) are used as catalysts.