OSCILLATORY OXIDATION OF MN(II) IONS BY HEXACYANOFERRATES(III) AND BISTABILITY IN THE REDUCTION OF MNO2 BY HEXACYANOFERRATES(II) IN A CSTR

A new transition metal oscillator based on the oxidation of Mn2+ ions by Fe(CN)(6)(3-) ions in a CSTR has been found. As well as the oscilla tions of the absorbance of the Mn(IV) species, pH-oscillations have be en observed. In the reduction of manganese dioxide by Fe(CN)(6)(4-) io ns a kinetic bistability has been described, A skeleton mechanism desc ribed recently for Mn(II)-H2O2 and Mn(II)-Br-2 oscillators has been ap plied here and further developed by the idea of the catalytic activity of colloidal particles and of the assistance of the pi-I-value change of both main processes, i.e. of the Mn(II) oxidation by Fe(CN)(6)(3-) ions and of the Mn(IV) reduction by Fe(CN)(6)(4-) ions. This appears to be the first case where both sides of a reversible reaction are aut ocatalytic.