Micellar effects on the kinetics of cerium(IV) oxidation and the cerium(IV)-catalyzed Belousov-Zhabotinsky reaction with methyl-, ethyl-, or benzylmalonic acid

The kinetics of the oxidation of methyl- (MeMA), ethyl- (EtMA), or benzylma lonic (BzMA) acid by eerie ions and the Ce(IV)-catalyzed Belousov-Zhabotins ky (BZ) reaction with these substrates have been studied at 20.0 degrees C in stirred batch conditions in the absence and the presence of the cationic surfactant cetyltrimethylammonium nitrate (CTAN). Some measurements have a lso been performed using the anionic surfactant sodium dodecyl sulfate (SDS ). Addition of increasing amounts of CTAN has a little inhibitory influence on the redox process with MeMA and EtMA, whereas it causes a significant e nhancement with BzMA. Small decreasing rate effects are observed in the pre sence of SDS. In the absence of surfactants, the BZ systems with MeMA and E tMA show oscillatory behavior after an induction period, whereas no oscilla tions are found with BzMA, Tn the presence of CTAN all the systems exhibit oscillations after an induction period that is shortened markedly with incr easing CTAN concentration and that, at constant [CTAN], increases in the or der BzMA < MeMA < EtMA. Added CTAN also affects the oscillation period and the duration of the raising portion of an oscillatory cycle. The surfactant SDS affects these oscillatory parameters to a different extent. Explanatio ns of the experimental results are provided.