Malonic acid concentration as a control parameter in the kinetic analysis of the Belousov–Zhabotinsky reaction under batch conditions

Abstract

The influence of the initial malonic acid concentration [MA]₀ (8.00 × 10⁻³≤ [MA]₀≤ 4.30 × 10⁻² mol dm⁻³) in the presence of bromate (6.20 × 10⁻² mol dm⁻³), bromide (1.50 × 10⁻⁵ mol dm⁻³), sulfuric acid (1.00 mol dm⁻³) and cerium sulfate (2.50 × 10⁻³ mol dm⁻³) on the dynamics and the kinetics of the Belousov–Zhabotinsky (BZ) reactions was examined under batch conditions at 30.0 °C. The kinetics of the BZ reaction was analyzed by the earlier proposed method convenient for the examinations of the oscillatory reactions. In the defined region of parameters where oscillograms with only large-amplitude relaxation oscillations appeared, the pseudo-first order of the overall malonic acid decomposition with a corresponding rate constant of 2.14 × 10⁻² min⁻¹ was established. The numerical results on the dynamics and kinetics of the BZ reaction, carried out by the known skeleton model including the Br₂O species, were in good agreement with the experimental ones. The already found saddle node infinite period (SNIPER) bifurcation point in transition from a stable quasi-steady state to periodic orbits and vice versa is confirmed by both experimental and numerical investigations of the system under consideration. Namely, the large-amplitude relaxation oscillations with increasing periods between oscillations in approaching the bifurcation points at the beginning and the end of the oscillatory domain, together with excitability of the stable quasi-steady states in their vicinity are obtained.