【作者】 赵长春；

【导师】 高庆宇；

【作者基本信息】 中国矿业大学 ， 化学工艺， 2011， 博士

【摘要】 在碱性介质条件下铜离子催化过氧化氢氧化硫氰酸盐反应是为数不多的几个在封闭以及开放体系都存在非线性振荡的体系。本文利用化学发光检测手段、电位在线测量技术测定了体系中丰富的非线性现象,并系统地考察了反应物浓度、流速以及温度等条件对体系非线性行为的影响。另外,采用毛细管电泳手段对碱性条件下过氧化氢氧化硫氰酸盐过程中反应物、中间产物以及生成物进行跟踪测量,提出了反应机理模型并进行了机理分析和数值模拟,与实验现象基本吻合。具体内容有如下几点:⑴利用低浓度的鲁米诺作为化学发光探针,系统地测量了封闭体系中各组分浓度对振荡反应体系非线性行为的影响。实验发现,改变组分浓度对振荡曲线的频率和振幅都有很大的影响。铜离子的浓度的增加使得曲线周期缩短,振幅减小,而振荡寿命基本不变（当浓度很高时,振荡寿命缩短）;体系诱导期随着硫氰根浓度增大而显著增加,主要是由于硫氰根的存在抑制了铜离子催化过氧化氢分解的催化活性,体系振荡寿命因为硫氰根浓度增大而使体系pH值降低的更快而缩短,在较强碱性条件下,低浓度的硫氰根有利于振荡反应的进行;碱性条件为振荡反应进行提供了必要的介质环境,当pH<9或者pH>13时,振荡反应终止。⑵采用开放体系,系统考察对振荡曲线的振幅、频率等的影响因素进行了半定量分析,并对振荡曲线上两个振荡峰的可能形成机制进行推测,作者认为峰Ⅰ的形成是由于体系中羟基自由基氧化鲁米诺产生化学发光并叠加在峰Ⅱ上形成,而峰Ⅱ的化学发光峰应该为超氧自由基氧化鲁米诺所引起,两种自由基的生成与体系中铜离子的价态的相互转化密切相关,当[Cu^Ⅰ（SCN）_n]^1-n转化为[Cu^Ⅱ（SCN）_n]^2-n时生成羟基自由基,而由Cu^ⅠHO₂→[Cu^Ⅰ（SCN）_n]^1-n时产生超氧自由基。当向开放体系中加入少量的EDTA时,峰Ⅰ的振幅迅速减小而峰Ⅱ却基本不变。随着EDTA浓度的增加,降低了体系中Cu（Ⅱ）的有效浓度,导致两峰强度降低。实验还表明,EDTA的加入对体系的振荡周期基本不影响,这可归于Cu（Ⅱ）-EDTA配合物十分稳定,而Cu（Ⅱ）-EDTA与Cu（Ⅱ）之间的相互转变速度很快,不影响整个反应体系的周期变化。⑶首次采用卤离子选择性电极测定体系中电位动力学曲线,发现与传统的铂电位振荡曲线的相位明显不同,而且其电位的改变与体系中pH值变化关联度小,有利于对振荡核心物种的监测。与化学发光研究方法相比较,最明显的特点是碘离子选择性电位动力学曲线的位置（即电极电位的大小）受到反应物浓度的影响很小,几乎不变,据此推测应与振荡体系中关键自催化中间产物的含量密切相关,为以后对该体系的深入研究提供新的方法。⑷利用毛细管电泳分离分析技术,实时检测在碱性pH=9.85时,过氧化氢氧化硫氰根反应体系的反应物、中间产物以及生成物随时间变化的动力学曲线。与前人在酸性和中性条件下实验相比,在碱性条件下,无催化的过氧化氢氧化硫氰根反应速度很慢,硫氰根的初次氧化生成次硫氰根为反应的速控步,在pH=9.85时,该反应的表观反应速率为4×10^-5 mol^-1min^-1。次硫氰根自身的循环以及与铜离子催化过氧化氢分解反应之间的相互耦合机制是形成H₂O₂/SCN^-/Cu²⁺/OH^-体系非线性现象的根本原因,在前人工作的基础上,作者提出自催化反应以及负反馈机制以解释H₂O₂/SCN^-/Cu²⁺/OH^-体系复杂反应动力学行为。该论文有图43幅,表4个,参考文献225篇。更多还原

【Abstract】 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.更多还原