Chemiluminescent Kinetics And Mechanistic Catalysis In The H₂O₂ /SCN^-/Cu²⁺ /luminol Reaction System

The thiocyanate oxidation by hydrogen peroxide under copper ion catalysis in basic solution is a few systems that exists oscillatory behaviors in a batch and a continued stirred tank reactor （CSTR）. In this dissertation, the numerous nonlinear phenomenons has been acquired by chemiluminescence and potential monitoring measurement and the effects of variety of factors such as concentration of ingredient, flow rate and temperature have discussed systematically and detailed. In addition, the capillary electrophoresis technique was also applied in the thiocyanate oxidation by hydrogen peroxide in basic solutions, the reaction substance, the intermediate and the final products were monitored in the reaction process. The reaction mechanisms were put forward to elaborate the experiment results. The simulation results wrer agree with the experiment data. The main contents including the following parts:1. The ingredient effects on the nonlinear behaviors were systematically surveyed in a batch by means of chemiluminescence technique using low concentration luminol as the probe. It has found that the ingredient concentration has obvious effects on the oscillatory frequency and amplitude. The oscillation periods decrease with the copper（Ⅱ） concentration increase while the total oscillatory life keep constant （the oscillatory life cut down at the higher copper（Ⅱ） concentration）. The induction periods were dramatically increased with the raised thiocyanate concentration. The increased suppression on catalytic activity of copper（Ⅱ） at higher thiocyanate concentration and the quick pH drops were the main reasons for this appearance. At high pH values, the low thiocyanate concentration helps the oscillatory reaction. The appropriate basic condition is necessary for the oscillatory reaction and the oscillations are disappeared at pH<9 or pH>13.2. The influences of the ingredient concentrations on the oscillatory behaviors were studied through the amplitude, the period and peak height as the function of measure parameters in a CSTR. The dynamical structure of two peaks during a period was discussed in detail. The key species involving in the two-transformation process are inferred to be superoxide radical and hydroxyl radical generated in the system. The two radical generations were closely related to the copper valence conversion in the oscillatory system. When EDTA added in the system, the height of the two peaks were reduced due to the lessened free Cu（Ⅱ） content. It has also found that the EDTA addition have little effect on the oscillatory periods. This phenomenon may be due to the stable Cu（Ⅱ）-EDTA compound and the Cu（Ⅱ）-EDTA（?） Cu（Ⅱ） transformation are too fast to affect the periods.3. The halide ion selective electrode potential was first applied in the determination of the kinetic curves of the system, the obvious phase difference from the traditionally Pt electrode was found and the correlation of the iodide electrode and pH was little, hence, the core substance was easily determined. The Pt、bromide、iodide electrode potential kinetic curves were investigated systematic and the similar conclusions have received. It has guessed that the potential was closely related to the core oscillatory substance.4. Based on the capillary electrophoresis（CE） analysis technique, the kinetic curves of reactant, the intermediate and the product in the thiocyanate oxidation by hydrogen peroxide reaction at basic solution has been acquired. Compared to reaction in the neutral and acid media, the reaction rate is slower and the first thiocyanate oxidation by hydrogen peroxide is the key reaction step. It has found that the reaction apparent rate constant is 4×10^-5 mol^-1min^-1at pH = 9.85.The mutual coupling of the recycles of OSCN^- and free radical generated by hydrogen peroxide decomposition under copper ion catalysis were the key reaction step in the H₂O₂/SCN^-/Cu²⁺/OH^- complex kinetic system. The author has proposed the mechanism for the complex reaction based on the abundant nonlinear phenomena.This dissertation has 43 graphs, 4 tables, and 225 references.