Abstract
Oscillations in a Belousov - Zhabotinskii (B-Z) system having oxalic acid (OA) and glucose (G) as a mixed organic substrate, neither of which acts as a bromine scavenger, have been investigated. Studies have been performed for (i) varying the concentration of G while keeping the OA concentration fixed and (ii) varying OA but keeping G fixed in a batch reactor. In both cases upper and lower critical limits occur, between which oscillations are observed. Both single and double frequency oscillations have been observed in a wide range of concentrations of G as well as of OA. The induction period in most of the cases was <1 min. When G is fixed and OA is varied, the time pause between the sequential oscillations increases with an increase in OA. On the other hand when OA is fixed and G is varied, the time-pause decreases with an increase in G. The first type of oscillation is Br--controlled, whereas the second is non-Br--controlled. The order of addition of G and OA in the last has no influence on the induction period. It influences, however, the oscillatory characteristics. Br2 evolution in the G + OA + Ce 4+ + BrO3- + H2SO4 reaction system has been investigated spectrophotometrically. ESR and polymerization studies indicate the important role of free radicals in influencing the reaction mechanism. A tentative dual control mechanism has been suggested involving autocatalysis of HBrO2 and BrO2*
Original language | English (US) |
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Pages (from-to) | 4562-4567 |
Number of pages | 6 |
Journal | Journal of Physical Chemistry A |
Volume | 109 |
Issue number | 20 |
DOIs | |
State | Published - May 26 2005 |
Externally published | Yes |
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry