Chemical oscillator CIMA reaction

The chlorite-iodine reaction in a flow reactor at relatively high (10 M) input concentrations of CIO and I" is, of course, a chemical oscillator. However, these oscillations do not occur at the lower concentrations used in the CIMA and CDIMA systems because the key intermediates cannot accumulate to sufficiently high levels. 

The chemical system used for our study is a chlorite-iodide-malonic acid (CIMA) reaction in an acidic (sulfuric acid) aqueous solution. The CIMA reaction exhibits a rich variety of phenomena oscillations in a batch reactor or in a CSTR [26], transient target waves in a closed Petri dish [26], bistability in a CSTR [26, 27], front structures in a Couette reactor [27-30], and Turing patterns in open gel reactors [7-10]. In our two-side-fed reactor. Figure lb, components of the reaction are distributed in the two compartments in such a way that neither compartment is separately reactive. Chlorite is only in compartment A , and malonic acid is only in compartment B thus there are opposing chemical concentration gradients in the direction normal to the plane of the gel. The other chemical species are contained in equal amounts in both reservoirs, except for sulfuric acid, which is more concentrated in compartment B than in compartment A. Note that chlorite and iodide in compartment A are at a low acid concentration they would react rapidly at high acid conditions. 

The spatio-temporal patterns observed when performing numerical simulations of the reaction-diffusion model (3) are in many respects very similar to those observed experimentally in the Couette flow reactor with the CIMA reaction [31, 59-64]. This reaction provides a remarkable illustration that stationary and oscillating front patterns can organize in a chemical system from the diffusive coupling of steady state reactor cells. The aim of this section is to detail some specific transitions leading to spatio-temporal patterns... 

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