I. Hanazaki et G. Rabai, ORIGIN OF CHEMICAL-INSTABILITY IN THE BROMATE-SULFITE FLOW SYSTEM, The Journal of chemical physics, 105(22), 1996, pp. 9912-9920
The origin of the instability observed in the bromate-sulfite-proton s
ystem is discussed. This is known as the subsystem of some pH oscillat
ors which provides the positive feedback channel for H+. It is compose
d of the following two fast equilibria: H+ + SO32- <-> HSO3- and H+ HSO3- <-> H2SO3 and the oxidation of HSO3- and H2SO3 by BrO3- to recov
er the initially supplied proton as 3HSO(3-) + BrO3- --> 3SO(4)(2-) Br- + 3H(+) and 3H(2)SO(3) + BrO3- --> 3SO(4)(2-) + Br- + 6H(+). This
scheme exhibits bistability under flow conditions. It gives rise to ch
emical oscillations if it is coupled with a simple linear decay proces
s of H+ as a negative feedback channel. It is also capable of exhibiti
ng chaotic behavior in the presence of HCO3-. We analyze the nature of
the strong nonlinearity provided by the above scheme in detail and sh
ow that it arises essentially from the fast reaction of H2SO3 with bro
mate. The simplicity of the scheme enables us to describe the system d
ynamics with three variables without any approximation. As a result, w
e now have a model in hand in which we can compare the theoretical res
ults directly and quantitatively with the corresponding experiments. T
his situation may open a way to understand the complexity in nonlinear
chemical systems in a more quantitative manner. Some recent experimen
tal findings of complex oscillatory behavior including chaos for the s
ystem with more realistic negative feedback channels, or for the syste
m in which BrO3- is replaced with H2O2, are discussed on the basis of
the present analysis. (C) 1996 American Institute of Physics.