非缓冲介质中硫脲氧化的非线性动力学

研究了在非缓冲介质中高碘酸盐氧化硫脲的复杂反应动力学。实验结果表明：高碘酸盐氧化硫脲的非线性反应不但呈现多种不同的化学计量方程式,而且体系的pH、I-]、I2]及Pt电极电位呈现封闭条件下的准振荡和单峰振荡以及开放条件下的双稳态和衰减振荡行为。综合考虑硫价态与碘价态变化的各自非线性过程及相互耦合,提出了包含质子快速预平衡反应、碘化合物自身反应、碘化合物-硫化合物反应以及硫－硫反应的12步反应机理,模拟出了封闭体系中pH、I-]以及I2]的准振荡和单峰振荡以及开放体系中的双稳态行为。

Nonlinear Oxidation of Thiourea in an Unbuffered Medium

The reaction between periodate and thiourea has been studied in an unbuffered medium. A variety of interesting dynamical behavior including variable stoichiometries, characteristic "clock reaction" and oligooscillations or single peak oscillations in pH, the concentrations of both iodide and iodine were found in a closed reactor. When studied in an open reactor, the above reaction system displays fascinating damped oscillations and bistability in an unbuffered aqueous solution. A 12‐step simplified mechanism has also been proposed here. Our investigation illustrates that it is critical to include a rapid H⁺‐mediated preequilibrium step in the suggested mechanism. The modified mechanism gives a better agreement between the calculated results and experimental observations.