The response of the Belousov-Zhabotinsy (BZ) system to the addition of increasing amounts of the anionicsurfactant sodium dodecyl sulfate (SDS) was monitored at 25.0 °C in stirred batch conditions. The presenceof SDS in the reaction mixture influences the oscillatory parameters, i.e., induction period and oscillationperiod, to an extent that depends on the surfactant concentration. The experimental results have shown thatthe induction period increases slightly on increasing surfactant concentration and, then, a further increase inthe [SDS] leads to an enhancement while the oscillation period increases monotonously on increasing SDSconcentration. It has been proposed that the response of the oscillatory BZ system to the addition of SDS isdue to the peculiar capability of the organized surfactant assemblies to affect the reactivity by selectivelysequestering some key reacting species. Indeed, explanations of the experimental results have been given onthe basis of the role played by the micellar shape, which in turn dictates the hydrophobic nature. The suggestedperturbation effects have been supported by performing viscosity measurements on the aqueous SDS solutionsand by the spectrophotometric estimation of the binding constant of the bromine species to the micellaraggregates. This study has indirectly corroborated the existence of two kind of micelles and unambiguouslyrevealed that the bromine species show a different affinity toward the spherical and rod-like micelles.
|Rivista||JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL|
|Stato di pubblicazione||Published - 2007|
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