不同粒径的零价锌活化过硫酸钠降解偶氮染料甲基橙及刚果红的研究

发布时间：2019-03-16 18:15

【摘要】：随着经济的快速发展,环境污染问题日趋严重,其中,水污染问题尤为突出。偶氮染料作为主要的污染源,以其复杂的结构、较强的毒性、难以生化等特点危害着环境,因此偶氮染料的降解问题日益成为国内外科学家们研究的重点。高级氧化技术的发展为染料的彻底降解提供了可能。已有报道关于羟基自由基降解有机污染物的降解机理,而又有一些研究者发现了氧化性更强的硫酸根自由基。零价金属活化过硫酸盐是生成硫酸根自由基的一种方法,而不同粒径的零价金属对硫酸根自由基的产生发挥着不同的作用,因此本文采用不同粒径的零价金属锌来活化过硫酸钠分别降解偶氮染料甲基橙和刚果红,找到最优的降解条件并推测可能的反应机理。论文分为以下两部分:第一部分:通过批次实验考察了不同粒径的零价锌(Zn~0)活化过硫酸钠(Sodium Persulfate,PS)降解偶氮染料甲基橙(Methyl Orange,MO)的降解效果,结果证明,不同粒径的Zn~0对活化PS降解MO有明显的差异性。Zn~0粒径越小,比表面积越大,表面活化作用越强,可以更充分地和PS发生反应,降解MO效果更好。反应过程中有强氧化性的硫酸根自由基(SO4-)和羟基自由基(·OH)产生。反应开始时速度很快,之后变缓,最后又变快。主要是SO_4~(·-)猝灭、SO_4~(·-)降解MO、SO_4~(·-)和OH-反应,三者相互作用的结果。另外,pH、PS浓度、Zn~0初始浓度也对降解MO都有明显的影响,实验最终得出降解MO的最佳条件为:pH=4,PS浓度=10 mg/L,Zn~0初始浓度=1.5 g/L,Zn~0粒径为150 μm。最佳条件下,MO的脱色率为87%,TOC降解率为37%,COD降解率为55%。第二部分:通过批次实验对不同粒径的零价锌(Zn~0)活化过硫酸钠(Sodium Persulfate,PS)降解偶氮染料刚果红(Congo red,CR)进行了研究。零价锌的粒径按照大小分为三种:小于150 μm、150 μm-300μm和大于300 μm。结果表明,随着零价锌粒径的减小,刚果红的脱色率、矿化率、COD降解率依次升高。另外,溶液的初始pH、PS浓度和Zn~0的浓度也对降解CR都有明显的影响,实验最终得出降解CR的最佳条件为:pH=6,PS浓度=150mg/L,Zn~0初始浓度=1.5g/L,Zn~0粒径小于150μm。最佳条件下,CR的脱色率为86%,TOC降解率为55%,COD降解率为72%。
[Abstract]:With the rapid development of economy, the problem of environmental pollution is becoming more and more serious, especially the problem of water pollution. Azo dyes as the main source of pollution, because of its complex structure, strong toxicity, difficult to biochemical characteristics such as endangering the environment, so the degradation of azo dyes has increasingly become the focus of scientists at home and abroad. The development of advanced oxidation technology provides a possibility for the complete degradation of dyes. The mechanism of degradation of organic pollutants by hydroxyl radical has been reported, and some researchers have found that sulfate radical with stronger oxidizability has been found. Activation of persulfate by zero-valent metals is a method of generating sulfate radical, and different sizes of zero-valent metal play a different role in the production of sulfate radical. In this paper, zinc with different particle sizes was used to activate sodium persulfate to degrade methyl orange and Congo red respectively. The optimum degradation conditions were found and the possible reaction mechanism was deduced. The paper is divided into two parts as follows: part one: the degradation effect of zinc zero valence (Zn~0) activated sodium persulfate (Sodium Persulfate,PS) on the degradation of azo dye methyl orange (Methyl Orange,MO) was investigated by batch experiments. The smaller the particle size of Zn ~ 0 and the larger the specific surface area, the stronger the activation effect of surface, which can react with PS more fully, and the degradation of MO is better. The Zn~0 with different particle size has obvious difference in the degradation of MO. During the reaction, strong oxidized sulfate radical (SO4-) and hydroxyl radical (OH) were produced. The reaction starts quickly, then slows down, and finally gets faster. It is mainly the result of the SO_4~ (-) quenching, the degradation of MO,SO_4~ (-) by SO_4~ (-) and the reaction of OH-. In addition, both the concentration of pH,PS and the initial concentration of Zn~0 have obvious effects on the degradation of MO. The optimum conditions for the degradation of MO are as follows: pH=4,PS concentration = 10 mg/L,Zn~0 initial concentration = 1.5g / L, particle size of pH=4,PS 0 = 150 渭 m. Under the optimum conditions, the decolorization rate of MO is 87%, the degradation rate of TOC is 37%, and the degradation rate of COD is 55%. Part two: the degradation of azo dye Congo red (Congo red,CR) by zinc zero valence (Zn~0) activated sodium persulfate (Sodium Persulfate,PS) with different particle sizes was studied by batch experiments. The particle size of zero-valence zinc is divided into three types according to its size: less than 150 渭 m, 150 渭 m-300 渭 m and more than 300 渭 m. The results showed that the decolorization rate, mineralization rate and COD degradation rate of Congo red increased with the decrease of zinc particle size. In addition, the initial concentration of pH,PS and the concentration of Zn~0 have obvious effects on the degradation of CR. The optimum conditions for degradation of CR are as follows: pH=6,PS concentration = 150mg / L, initial concentration = 1.5g / L, particle size less than 150mg 路m ~ (- 1), and the optimum conditions are as follows: pH=6,PS concentration = 150mg / L, initial concentration = 1.5g / L, particle size less than 150mm. Under the optimum conditions, the decolorization rate of CR is 86%, the degradation rate of TOC is 55%, and the degradation rate of COD is 72%.
【学位授予单位】：南京农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X788

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