【作者】 李惠；

【导师】 兰叶青；

【作者基本信息】 南京农业大学 ， 应用化学， 2014， 硕士

【摘要】 偶氮染料在化工行业应用广泛,主要用于纺织品、皮革、印染等。偶氮染料分子结构中含有偶氮键,常与苯环相连构成共轭体系,能分解出对人体具有致癌、致畸、致突变的三致作用的芳香胺中间体。从生产、运输、使用、废弃物排放等环节进入环境中,为人类的生存环境带来重大威胁。由于大多偶氮染料结构比较复杂,可生化性差,传统单独的物理、化学、生物方法难以降解,因此,寻求高效、廉价、环境友好的处理方法具有重要的理论和现实意义。零价金属可以有效地还原降解许多有机污染物,且价廉易得,所需工艺简单,具有广阔的应用前景。硫酸根自由基(SO4-)近年来开始用于降解环境中的有机污染物,其标准氧化还原电位E0=2.60 V,接近羟基自由基.OH(E0=2.80 V),理论上可氧化降解绝大部分有机物。本文主要研究零价锌粉活化过硫酸钠产生硫酸根自由基降解偶氮类染料甲基橙和刚果红的影响因素以及反应机理。本论文分为两部分：第一部分：通过批式试验研究pH、温度、反应物的初始浓度、锌粉和过硫酸钠的用量等因素对脱色降解单偶氮染料甲基橙的影响及其机理。结果表明：锌粉活化过硫酸钠对降解甲基橙有很好的效果,降解甲基橙的反应分三个阶段,快速反应的第一阶段,平稳缓慢地第二阶段,以及较为快速反应的第三阶段,并且第三阶段反应符合一级反应动力学方程。通过CODCr、TOC、HPLC分析对脱色矿化程度进行了监测。并通过加入自由基淬灭剂叔丁醇和左旋组氨酸,验证了反应过程中羟基自由基和硫酸根自由基的存在,其中硫酸根自由基起主导作用,从而探索降解机理。第二部分：通过批式试验研究验证pH、温度、反应物的初始浓度、锌粉和过硫酸钠的用量等因素对脱色降解双偶氮染料刚果红的影响及其机理,并与单偶氮染料甲基橙的降解进行对比。结果表明：单独锌粉对刚果红具有较好的脱色效果,但矿化程度不理想,而锌粉活化过硫酸钠对脱色和降解矿化刚果红依然有较好的效果,降解刚果红的反应分两个阶段,第二反应阶段符合一级反应动力学方程。自由基淬灭剂(叔丁醇和左旋组氨酸)的加入,同样验证了反应过程中羟基自由基和硫酸根自由基的存在,其中硫酸根自由基起主导作用；通过CODCr、TOC、HPLC分析对降解矿化程度进行监测,通过EPR技术,对反应过程中的自由基种类进行鉴定,从而验证推理的可能降解途径。更多还原

【Abstract】 Azo dyes are widely used in the chemical industry, mainly for textiles, leather, printing and dyeing. The conjugated system is formed by benzene rings linked with azo bond in the molecular structure of azo dyes which are carcinogenic, teratogenic and mutagenic due to aromatic amine intermediate. Owing to the complex structure, poor biodegradability of azo dyes, the traditional physical, chemical and biological methods are difficult to make them degrade efficiently. Therefore, it is of important theoretical and practical significance to seek efficient, inexpensive and environment-friendly method to deal with azo dyes. Zn0-activated persulfate (PS) is a novel advanced oxidation technology for the degradation of organic pollutants in aqueous solution. Sulfate radical (SO4·-) produced in this system can degrade most of the organic matter theoretically. In this paper, the influencing factors and the reaction mechanism for degradation of azo dyes (methyl orange and congo red) by sodium persulfate activated with zero-valent zinc were investigated.This thesis is divided into two parts:Part I:The effects of the initial solution pH, the dosages of PS and Zn0, and the temperature were investigated through a series of batch experiments using methyl orange (MO), an azo dye, as a model organic pollutant. The results demonstrated that MO could be effectively degraded by Zn0-activated PS. The chemical oxygen demand (COD) and the total organic carbon (TOC) decreased by approximately 85 and 58%, respectively, in the solution containing 98 mg/L MO at the initial pH 5 and 25℃ within 3 h. Tertiary butyl alcohol, an ·OH-specific radical scavenger, and L-histidine, a universal radical scavenger, corroborated that both ·OH and SO4-· contributed to MO degradation, and SO4-· plays a leading role. Three stages were observed during the degradation of MO at 15 and 25℃, a rapid removal of MO in the initial stage of the reaction, followed by a very slow one and then a relatively quick degradation process. In the third stage of the reaction, the degradation of MO obeyed the first-order kinetics.Part Ⅱ:A disazo dye (congo red, CR) was adopted to study the similarity and difference of the degradation of different azo dyes by Zn0-activated PS. The effects of the initial solution pH, the dosages of PS and Zn0, and the temperature were investigated by batch experiments. The results showed that decoloration effect of congo red by single zinc is good, but the mineralization extent is not ideal. However, CR could be effectively degraded by Zn0-activated PS, which means both good decoloration and mineralization effect. The degradation of Congo red reaction can be divided into two stages, and the second reaction stage obeyed the first-order kinetics. The mineralization was monitored by CODcr, TOC, HPLC analysis technology, and the free radical species in the reaction process was identified by EPR technology to discuss and verify the possible degradation mechanisms.更多还原