亚氯酸盐-硫代硫酸盐非缓冲体系的动力学

Complex Kinetics of the Chlorite-Thiosulfate in an Unbuffered Reacti on System

研究了亚氯酸盐-硫代硫酸盐反应体系在非缓冲条件下的复杂动力学行为.结果发现,在开放体系中反应的pH值和Pt电位存在准周期振荡分叉和混合模式振荡分叉通向混沌的过程,且pH峰与Pt电位峰反相位.当[ClO2-]与[S2O32-]起始浓度比相对较小时,随着流速的逐渐升高,体系的pH值和Pt电位从简单的小振幅振荡(S)经过准周期振荡分叉到混沌,最后回到简单大振幅振荡(L);而当[ClO2-]与[S2O32-]起始浓度比相对较高时,随着流速的降低,体系的pH值和Pt电位出现LS1、LS2、LS3…LSn的混合模式振荡,并在每对(LSn、LSn+1)振荡区间发现了LSn、LSn+1随机出现的非周期振荡行为.运用硫价态变化的一般动力学模型,模拟出了反应体系的混合模式振荡及非周期振荡.

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.