【作者】 王萍；

【导师】 杨世迎；

【作者基本信息】 中国海洋大学 ， 环境工程， 2010， 硕士

【摘要】 传统的高级氧化技术是基于羟基自由基(·OH)的氧化技术,基于硫酸根自由基(S04-·)的过硫酸盐高级氧化技术是近年来刚刚兴起的新型高级氧化技术,具有良好的发展前景。活化方法的研究是目前过硫酸盐高级氧化技术研究的热点问题。现有的过硫酸盐活化方法主要包括热、紫外光、过渡金属三种。本文以水中典型的难降解有机物金橙Ⅱ为模型污染物,首先分析了H2O2、过一硫酸盐(PMS)和过二硫酸盐(PS)在热、紫外光、阴离子活化条件下的差异,以此为基础研究了最佳组合(热/PS、紫外光/PS)及新型活化方法CO32-/PMS、微波/PS对金橙Ⅱ的降解动力学、影响因素和反应机理。具体研究内容如下：(1)H2O2是研究和应用最多的过氧化物,PMS和PS属于H2O2的衍生物。三者在结构上相似但也存在不同。结构的差异使三者在不同活化条件下对有机物的降解速率和机理不同。本实验首先分析了PMS、PS与H2O2在热、紫外光、阴离子活化方法下对有机物降解效率差异,为接下来的研究奠定了基础。研究结果发现在热活化条件下三种过氧化物对金橙Ⅱ的降解速率为PS>>PMS>H2O2,紫外光活化条件下降解速率为PS>H2O2>PMS,PMS可以被阴离子(CO32-、HCO3-、HPO42-、Cl-)活化,而PS和H2O2不能被活化。(2)由(1)中的研究可知,在热活化条件下PS降解效果最好。而我国每年都会排放大量的高温废水(例如印染废水等),高温废水由于其较高的温度给废水处理处理带来极大的困难。因此,本实验研究了利用高温印染废水的余热活化PS降解染料的可能性。结果表明：温度高于50℃可活化PS降解金橙Ⅱ；pH值为中性时降解效果最好；通过紫外可见光谱UV-vis和总有机碳TOC分析得知,金橙Ⅱ不仅被脱色,苯环和萘环也可以被降解,TOC也能被有效去除；在体系中S04-’和.OH都起到降解作用,但是SO4-·占主导地位。(3)由(1)中的研究可知在紫外光活化条件下PS降解金橙Ⅱ的效果最好,本实验以金橙Ⅱ为模型污染物对紫外光活化PS降解金橙Ⅱ进行了研究。实验结果表明：紫外光波长为254 nm时可活化PS产生SO4-·降解金橙Ⅱ；降解速率随PS浓度的增加而加快；中性pH时降解效果最好；紫外光活化PS不仅可以将金橙Ⅱ脱色也可以有效地降解苯环和萘环,TOC也能被有效去除；SO4-·在降解过程中起主要作用。(4)由(1)的研究结果知道,阴离子可以活化PMS产生活性物种降解有机物,尤其以CO32-的效果最好。CO32-是水中常见的阴离子,在天然水体和废水中广泛存在。本实验研究了CO32-活化PMS对金橙Ⅱ的降解情况。实验结果表明：CO32-是一种高效活化PMS的方法,即使在极低的浓度下(0.001 mol/L)仍然能活化PMS降解金橙Ⅱ。另外,金橙Ⅱ在可见区和紫外区的官能团均都被破坏,TOC也能被有效的去除。甲醇(MA)和NaN3作为俘获剂研究初步探讨了CO32-活化PMS的机理。结果发现与其他活法方法不同,CO32-活化PMS并没有产生S04-·,而是可能产生了102。(5)微波加热是分子水平的加热,具有均匀快速的特点,具有降低反应活化能、缩短反应时间、增强选择性、加快反应速率等优点。活性炭是优良的微波吸收材料,能吸收微波的能量并转化为热能。本实验研究了微波活化PS对金橙Ⅱ的降解情况。实验结果表明：微波活化PS最大的优点是快速、对高浓度废水降解效果好。例如：20-1000 mg/L的金橙Ⅱ在5-7 min内都能实现100%的脱色。活性炭加强了微波活化PS体系的氧化能力和对有机物的降解能力。(6)氯离子(Cl-)是污水及海水中常见的无机离子,是一种优良的羟基自由基俘获剂,不利于高级氧化技术技术对有机物降解。本实验研究了Cl-对四种典型过硫酸盐活化方法的影响,并对其影响机理进行了初步探讨。结果表明：在UV/PS和热/PS氧化体系中,由于Cl-与S04-·反应生成C12-·,从而对金橙Ⅱ的降解产生了不利影响；在UV/PMS体系中,随着由于Cl浓度的增加,有HClO生成,对反应有促进作用；在Co2+/PMS体系中,Cl-限制了Co2+/Co3+的循环,抑制了反应了SO4-·产生,此时HClO起重要的降解作用。更多还原

【Abstract】 Advanced oxidation technologies, in which peroxydisulfate (PS) or peroxymonosulfate (PMS) is used as oxidant, came forth recently for the degradation of non-biodegradable contaminants. PS and PMS can be activated to generate SO4-·which is also a powerful oxidant and can oxidize most organics in wastewater. The study of activation method is a hot issue. The conventional activation methods consist of heat, UV and metal activation. While some new activation method come forth recently. In this study, azo dye Acid Orange 7 (AO7) was chosen as the model contamination to study the degradation rate, influential factor and radical method under heat and UV activation method (conventional activation method) and CO32- and microwave activation method (new activation method). Besides, the effect of Cl-, which is an efficient quenching reagent, was studied. Specific studies are as follows:1) The three peroxides mentioned above (PS, PMS and H2O2) are similar in structure and they all have O-O bond. On the other hand, they have some difference in structure which results various degradation rates and radical mechanisms under various peroxides activated method. Therefore, the main objectives of this study are: (1) to compare the degradation efficiencies of A07 by these three peroxides (PS, PMS, H2O2) under heat or UV activation condition; (2) to study whether common anions (SO42-, NO3-, CO32-, HCO3-,HPO42-, Cl-) can activate these peroxides and consequently degrade A07. The results show that the order of A07 degradation efficiencies by heat activation is PS >> PMS> H2O2 and the order by UV activation is PS> H2O2> PMS. In the anions activated method, it was found that PMS could be activated by some anions, but PS and H2O2 can not be.2) High-temperature wastewater constitutes one of the largest groups of organic compounds that represent an increasing environmental danger. It is reported that billion tons high-temperature printing and dyeing wastewater discharge every year in china. The goal of this study is to use the high-temperature wastewater as heat resource to activate PS to degrade contamination in wastewater. The result indicated that the higher temperature of wastewater can result in the faster degradation rate. The radical quenching experiments demonstrate that both SO4-·and·OH could degrade AO7 but SO4-·plays the dominant role. Maximum AO7 degradation occurred at pH 7. Heat activated PS could not only decolorize AO7 but also mineralize it.3) The aim of this experiment is to study the degradation of AO7 by PS under UV activated method. The results showed that PS could be activated by UV (254 nm). The higher temperature of wastewater can result in the faster degradation rate and maximum AO7 degradation occurred at pH 7. UV activated PS could not only decolorize AO7 but also mineralize it. The radical quenching experiments demonstrate that both SO4-·and·OH could degrade AO7 but SO4-·plays the dominant role.4) CO32- is common anions in natural water and wastewater. The existence of CO32-, which has been considered as an efficient quenching reagent by competing with radicals, can retard the degradation rate of organic compounds in the AOPs. The main objectives of this experiment are to study the degradation of AO7 by CO32- activated PMS. The results show that CO32-activated is an effective activated method. CO32-activated PS could not only decolorize AO7 but also mineralize it. The radical quenching experiments demonstrate that 1O2 other than SO4-·plays the dominant role.5) Microwave heating can decrease activation energy, reduce reaction time, increase the selectivity of reaction and improve the speed of reaction, and etc. Activated carbon (AC), which is an excellent MW absorbing material, could absorb and convert MW energy into thermal energy. The goal of this experiment is to study degradation of AO7 by microwave activated PS. The results show that the biggest advantage of microwave activation PS is fast. AO7 (up to 1000 mg/L) is completely decolorized within 5-7 min. The present of activated carbon enhance the oxidation of microwave/PS systems, improving the organic matter degradation.6) Cl- is common anions in natural water and wastewater. The existence of Cl-, which has been considered as an efficient quenching reagent by competing with radicals, can retard the degradation rate of organic compounds in the AOPs. The effect of Cl- on the degradation of AO7 by PS and PMS under various activated conditions (UV (254 nm)/PS, Thermal (70℃)/PS, UV/PMS, Co2+/PMS) and the role of active chlorine oxidizers (Cl2-·, HClO) generated from the reaction of Cl- with SO4-·or·OH were investigated by using quenching method. The results show that under UV/PS and heat/PS, Cl- inhibited AO7 degradation due to reaction of Cl- with SO4-·to generate Cl2-·and HClO. Under UV/PS condition, with the increased of Cl-, the amount of HClO increases and the degradation rate accelerates. Under Co2+/PS condition, Cl- can restrain the circulation of Co2+ and Co3+and hinder the formation of SO4-更多还原