The transition from pH waves to iodine waves in the iodate/sulfite/thiosulfate reaction-diffusion system

Nonlinear spatial temporal behavior of the iodate/thiosulfate/sulfite reaction is investigated both in a stirred and spatially extended media. In accord with the temporal dynamics in the homogeneous media, both propagating fronts and target patterns ore achieved in the spatially extended medium. On increasing the iodate concentration the system evolves from exhibiting propagating fronts to circular waves and then shows target patterns and finally the iodine waves. Influences of concentrations of sulfite, thiosulfate and acid on the reaction kinetics and pattern formation are also investigated systematically, and transitions from pH waves to iodine waves con be achieved via adjusting the concentration of the three species. The propagation velocities of pH and iodine waves ore understood with the quadratic and cubic autocatalysis of proton and iodide respectively.