Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (08): 762-765.doi: 10.3866/PKU.WHXB20030818

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Complex Kinetics of the Chlorite-Thiosulfate in an Unbuffered Reaction System

Wang Shun;Gao Qing-Yu;Wang Xin-Hong;Lin Juan-Juan;Lai Shun-An;Mo Yan-Xue   

  1. College of Chemical Engineering, China University of Mining and Technology, Xuzhou, 221008; Department of Chemistry and Material Science, Wenzhou Normal College, Wenzhou 325027
  • Received:2003-01-07 Revised:2003-03-12 Published:2003-08-15
  • Contact: Gao Qing-Yu

Abstract: The complex kinetics of ClO2―-S2O32- nonlinear reaction system in an unbuffered solution has been investigated in a CSTR. Both quasiperiodic and mixed-mode oscillations of pH and Pt potential were observed. At relatively low [NaClO2]0/[Na2S2O3]0 ratio, the system changed from small-amplitude oscillations and quasiperiodic oscillations to chaos and pure large-amplitude oscillations with increasing the flow rate. At higher initial concentration ratio, however, quasiperiodicity was given way to mixed-mode oscillations in which each period consists of one large and n small peaks (LSn). LS, LS2,LS3,…, LSn were obtained when the flow rate was decreased. For a narrow range of flow rate between each pair of periodic regions(LSn, LSn+1), a region of aperiodic behavior, an apparently stochastic mixture of LSn and LSn+1, was also observed. A general model based upon changes in the oxidation state of sulfur in the presence of a generic oxidant simulated the mixed-mode oscillations and aperiodic behavior.

Key words: Quasiperiodic oscillations, Mixed-mode oscillations, Dynamic simulation