A TRANSITION-METAL OSCILLATOR BASED ON THE OXIDATION OF MN2-PEROXIDE(IONS BY HYDROGEN)

A transition-metal oscillator based on the oxidation of Mn2+ ions by h ydrogen peroxide in alkaline medium in a CSTR (continous-flow, stirred tank reactor) has been observed. Its design is described on the basis of the phase diagrams in [MnSO4](o)-k(o), [H2O2](o)-k(o) and pH-value -k(o) planes where k(o) (s(-1)) is the reciprocal reactor residence ti me. A reaction scheme of this new manganese chemistry based oscillator , consisting of an autocatalytic oxidation of Mn(II) by hydrogen perox ide, and of an autocatalytic reduction of manganese dioxide proceeding on a surface of colloids (MnO2)(col), is proposed. An autocatalytic o xidation of Mn(II) by aqueous hydrogen peroxide is alternated during t he oscillations with a micro-heterogeneous autocatalytic reduction of manganese dioxide.