Systematic design of chemical oscillators. 48. Chemical oscillators in group VIA: the copper(II)-catalyzed reaction between thiosulfate and peroxodisulfate ions

Sustained oscillations in redox potential, pH, and the concentration of dissolved O 2 are reported in the Cu(II)-catalyzed reaction between K 2 S 2 O 8 and Na 2 S 2 O 3 in a stirred tank reactor. A range of steady states is found, most of which can be unambiguously designated as either high or low pH, but there is no evidence of bistability. A free-radical mechanism in which Cu(I), Cu(III), and the radicals SO 4 .− and S 2 O 3 .− play key roles appears to be capable of accounting both for the observed kinetics of the batch reaction and for the oscillations in the flow system