Dual-frequency oscillations induced by acidity in Belousov-Zhabotinskii reactions with aldosugars as substrates

Depending on the initial concentration of H2SO4, two types of dual-frequency oscillations have been observed in Belousov-Zhabotinskii type reactions catalyzed by Mn2+ with acetone and aldosugars (arabinose, glucose, galactose, lactose or maltose) as coupled substrates in a batch reactor. No such dual-frequency oscillations have been found when a ketosugar like fructose was used instead of an aldosugar as the substrate; or acetone was replaced by N2 flow. No oscillations were observed when Ce3+ was used instead of Mn2+. The reaction products of aldosugars in different oscillating regimes have been analyzed. The dual-frequency oscillatory patterns have been discussed according to the roles of the substrates and their derivatives formed at different acidity.