SIMPLE AND COMPLEX PH OSCILLATIONS AND BISTABILITY IN THE PHENOL-PERTURBED BROMITE HYDROXYLAMINE REACTION

The unbuffered reaction between bromite and hydroxylamine at pH 3-7 ha s been studied under closed and open conditions. The stoichiometry of the batch system depends on the initial concentration ratio of the rea ctants and on the starting pH. The reaction is strongly autocatalytic in H+. Under flow conditions the reaction exhibits bistability between two steady states but does not oscillate. If the flow system is pertu rbed by an input of phenol, it shows oscillatory behavior in pH, poten tial of a Pt electrode, and color. A qualitative explanation of the ba tch and oscillatory behaviors is suggested. The bromite-hydroxylamine- phenol flow system can be characterized as a large-amplitude, long-per iod, pH-driven oscillator.