Bistability in reacting systems

We discuss below a few representative systems where (i) only bistability occurs and (ii) both bistability and oscillations occur. Bistability results for some typical chemical systems are discussed below. Quite a few different cases [6, 7] have earlier been discussed by Field and Burger [8]. 

Experimental studies [9] on Mn - - BrO system in CSTR have clearly established the existence of bistability (hysteresis loops) by (i) varying bromide ion inflow concentration, (ii) varying bromate ion inflow concentration, (iii) varying catalyst inflow concentration and (iv) varying flow rate and measuring the Br potential in the steady state. 

Geiseler and Follner [10] discovered bistability in cerous-bromate system and found that under certain set of constraints, the system in sulphuric acid medium can exist in either one or two stable states. Bar-Eli and Noyes [11] have explained their results on the basis of the following mechanism. 

By adding a flow term, the above set of equations yields seven rate equations. Using the appropriate computational procedure, these workers reported hysteresis limits and estimated bromide ion concentrations in steady states for various values of initial bromide ion concentration. 

For generating oscillations, a sub-system has to be added to the system under consideration. Such a sub-system is provided when malonic acid is added to the system. 

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On account of severe limitations, experimental studies on linear steady state could not be undertaken so far. However, the non-linear range experimental studies on bistability in reacting systems (Chapter 8) and chemical oscillations in CSTR do provide convincing examples of stable non-linear steady states under specific circumstances. 

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