Modelling complex transient oscillations for the BZ reaction in a batch reactor

The recent observations of transient complex oscillations in the Belousov–Zhabotinsky (BZ) reaction in a batch reactor are confirmed and an attempt is made to model this behavior using the Gyorgyi–Field mechanism (an extension of the classic Field–Körös–Noyes model). It is seen that the concentration of bromomalonic acid plays an important role, acting somewhat like a “slowly-varying parameter,” causing the system to sweep through a region of oscillatory response even in the absence of reactant consumption. Complex behavior is not observed in the model if the usual “pre-equilibrium” assumption in made for the intermediate species BrO2 but does arise if a full steady-state approximation is applied to this radical. These results may bring into question some assumptions made in the usual treatment of the cerium-catalyzed BZ system in closed reactors.