Generation of pH-Oscillations in Closed Chemical Systems: Method and Applications

All pH-oscillators reported to date function only under open (flow reactor) conditions. We describe an approach to generating pH-oscillations in a closed system by starting from an open system pH-oscillator, finding semibatch conditions under which it oscillates with an inflow of a single reactant to an otherwise closed reactor containing the remaining components, and replacing this inflow with a layer of silica gel impregnated with the key reactant. We present data showing the successful application of this technique to the BrO3- -Mn2+ -SO32- IO3- -Fe(CN)(6)(4-) -SO32-, and BrO3- -Fe(CN)(6)(4-) -SO32- systems. In all three cases, sulfite ion is the species that is replenished via dissolution from the gel layer.