Modeling the oscillatory bromate oxidation of ferroin in open systems

Abstract

A model for the ferroin-bromate-bromide-sulfuric acid system in a continuously stirred (flow-through) tank reactor has been constructed by extending the Noyes-Field-Thompson mechanism with the following composite processes: (a) ferroin-bromate, (b) ferroin-bromous acid, (c) ferroin-hypobromous acid, (d) ferroin-bromine, (e) ferriin-bromide, and (f) ferriin-bromine. The calculated high-amplitude oscillations and kinetic phase diagram are in good accordance with the experiments reported earlier. By completing the scheme with a reaction step accounting for the precipitation and dissolution of a ferroin-tribromide salt. the batch oscillations found at high concentrations of reactants can also be simulated. IntroductionThe Belousov-Zhabotinsky (BZ) oscillatory reaction, the cerium(II1)-catalyzed oxidation of malonic acid by acidic bromate, has been commonly applied during the last few decades for studying a wide variety of temporal and spatial instabilities in chemical

Spatio-Temporal Perturbation of the Dynamics of the Ferroin Catalyzed Belousov−Zhabotinsky Reaction in a Batch Reactor Caused by Sodium Dodecyl Sulfate Micelles

“…26,28 Nevertheless, to verify the influence of SDS micelles on this process, experiments on ferroin decomposition were conducted spectrophotometrically. Figure 1 shows the behavior of the ferroin absorbance along a wavelength scan (350 nm < λ < 600 nm), both in the absence (A) and in the presence (B) of the surfactant.…”

Competition between transport phenomena in a reaction–diffusion–convection system

“…The Belousov-Zhabotinsky reaction involves the oxidation of an organic species such as malonic acid by an acidified bromate solution in the presence of a metal ion catalyst Keki et al, 1992;Smoes, 1979;Taylor, 2002. In a closed system, the reaction typically exhibits a short induction period, followed by an oscillatory phase.…”

Dinâmica complexa no sistema bromato/hipofosfito/acetona/manganês e ferroína

“…Algumas vantagens importantes do sistema catalisado pela ferroína em comparação à receita original com cério são 24 : a presença de oscilações de grande amplitude no potencial redox de um eletrodo de platina, em fase com as mudanças de coloração e, as oscilações são geralmente observadas em uma ampla faixa de concentrações. Não obstante algumas similaridades, está claro que em variantes da reação de BZ utilizando ferroína como catalisador diferentes aspectos mecanísticos adicionais ao sistema tradicional com cério devem ser levadas em conta, de forma que a dinâmica não é capturada simplesmente pelo mecanismo FKN 18 .…”

“…Em termos cinéticos, Kéki et al 24 estudaram algumas reações entre ferroína/ ferriína e espécies como brometo, bromato e ácido bromoso. Uma das principais observações feita pelos autores consiste na constatação experimental de que, aparentemente em contraste ao sistema catalisado por íons cério, as espécies ferroína e ferriína apresentam acentuada reatividade frente a diferentes espécies presentes no meio reacional e não apenas ao radical BrO 2 .…”