A Completely Inorganic BZ-Type Oscillator in a Closed Homogeneous System

Article abstract of DOI:10.1246/bcsj.70.1539

In a batch reactor, an absolutely homogeneous inorganic Belousov-Zhabotinskii (BZ)-type oscillator has been designed in the system of BrO₃^--H₂PO₂^--Mn ²⁺-Fe(Phen)₃²⁺-H₂SO₄. The oscillations of both [Br^-] and [Mn³⁺]/[Mn²⁺] as well as [Fe(phen)₃³⁺]/[Fe(phen)₃²⁺] were observed by monitoring the changes of either the potential on a bromide electrode or the absorbance at the maximum absorbance wavelength for Mn³⁺ and Fe(phen)₃³⁺, respectively. Both of those two metallic ions are essential in the present system to give rise to the oscillations; their roles in the oscillation are discussed. It is found that Mn²⁺ can not be replaced by other substances, while Fe(phen)₃²⁺ can be replaced by either N₂ flow or acetone. However, it can not be replaced by other metallic ions, including Mn²⁺ and Ce³⁺. Those results suggest that Mn²⁺ is the real oscillating catalyst for an autocatalytic formation of HBrO₂ and Fe(phen)₃²⁺ is a catalyst for the catalytic reduction of Br₂ by H₂PO₂^- to remove any excess Br₂ produced during the oscillations.