【作者】 龙学军；

【导师】 甘复兴；

【作者基本信息】 武汉大学 ， 环境科学， 2015， 博士

【摘要】 染料废水(主要来源于精细化工中的染料加工业及染料集中使用的印染行业)因其排放水量大、组成成分复杂、色度深、有毒有害化合物含量高、难生物降解等特点历来是国内外公认的难治理的工业废水之一。寻找廉价、高效且具广泛应用范围的方法处理此类废水已经成为近年来科研工作者研究的热点。本论文工作构建了一种处理染料废水类Fenton新体系,即金属离子(Co2+和Cu2+)-碳酸氢钠(NaHCO3)过氧化氢(H2O2)体系。本文分别从类Fenton体系的构建、降解行为及影响因素、体系内各物种交互作用、活性物种的产生及染料降解机理等方面进行了较系统的探讨,得出一些创新性结论：(1)Co2+-HCO3--H2O2是一种作用于染料使之降解脱色的高效体系。Co2+、HCO3-、H2O2三者对于染料的降解缺一不可。50μM的酸性橙II(AOII)在5μMCo2+、 4mM H2O2、10mMNaHCO3的水溶液体系中经过10分钟的降解后能够完全脱色,比同样浓度的酸性橙II在含有50μM Fe2+的 Fenton试剂降解速度更快。此体系对于其他的染料如活性艳红(X-3B)、酸性桃红(SRB)、亚甲基蓝(MB)、罗丹明B(RhB)和甲基橙(MO)也有较好的脱色效果,另外在MB、SRB等其他染料以及一些常见阴离子和AOII共同存在时,Co2+-HCO3--H2O2体系能高效选择性降解AOII。(2)Co2+-HC03--H2O2体系中产生的羟基自由基是作用于染料脱色的活性物种,此类自由基是与金属配合物紧密结合在一起的非游离型键合羟基自由基。在反应过程中伴随着Co2+价态的变化：C02+首先被氧化成Co3+,随后部分被氧化的Co3+还原成Co2+。(3) Co2+-HCO3--H2O2体系中产生的羟基自由基与酸性橙Ⅱ(AOII)结合后攻击偶氮染料的两个C-N键,使得染料分解为苯酚磺酸、N2、1,2-萘醌及其进一步的氧化产物,提出了Co2+-HCO3--H2O2体系中酸性橙Ⅱ(AOII)降解的反应历程。(4) Cu2+-HCO3--H2O2体系也被证明为降解染料废水的高效体系。对于AOII、MO、MR、TB等染料均有较好的脱色效果。Cu2+-HCO3--H2O2体系内各物质会发生相互作用。Cu2+会与HCO3-形成多种配合物,在270nm的紫外区出现明显吸收峰。(5)自由基清除剂测量实验揭示了高氧化态的Cu(III)是对AOII的降解起主要作用的活性物种。在Cu2+-HCO3-中加入H2O2后,铜离子的价态发生改变。通过Cu(Ⅰ), Cu(Ⅱ)含量的变化推算出在反应60min后有体系中13%左右的Cu(111)的生成。Cu2+-HCO3--H2O2体系对于AOII的降解与Co2+-HCO3"-H2O2降解AOII的反应历程一样,也主要是通过AOII结构中的两个C-N键的断裂,使得染料分解为苯酚磺酸、N2、1,2-萘醌及其进一步的氧化产物。(6)发现Cu(Ⅰ)生成的动力学规律：Ca(Ⅱ)的生成速率随着过氧化氢浓度增大而增大,当过氧化氢浓度达到50mM时,其反应速率达到最大值,而碳酸氢钠浓度与反应速率表现出先增大后减小的趋势,在碳酸氢钠浓度为5mM时达到最大值。更多还原

【Abstract】 Treatment and disposal of dye wastewater has become one of the important fields in the environment problems around the world, due to that the dyes wastewater is highly colored, discharged wildly, harmful and hard to be biodegraded. Developing low-cost methods with highly efficiency and widely applied have gained more and more concerns. In this study, a simple, high catalytic efficiency new Fenton-like system was build in which simple irons (cobalt and copper) can activate H2O2 in bicarbonate aqueous solutions for the removal of dye pollutants. That is the metal ions (Co2+ and Cu2+)-sodium bicarbonate-hydrogen peroxide system. Some innovative conclusions were got by discussions of the construction of Fenton-like system, the degradation behavior、influence factors and the interactions of each species in system, the mechanism of dye degradation, which were systematically researched in this paper respectively.(1) Co2+-HC03--H2O2 was investigated as an effective system for the degradation of the dyes during which the role of Co2+、HCO3-、H2O2 are indispensable. Complete decolorization of 50 μM AOII was observed with 5 μM Co2+ ions and 4 mM H2O2 in 10 mM NaHCO3 aqueous solution after 10 min, which was much faster than that of Fenton reagent with 50 μM Fe2+ ions. The system was also useful for some other dyes degradation such as Reactive brilliant red, Sulforhodamine B, Methyl Orange, Methylene blue and Rhodamine B. Besides, In the presence of other pollutants such as methylene blue, SulforhodamineB or a significant amount of anions including Cl-， CO32-, SO42-, NO3-, HPO42- and CH3COO-, AOII was still rapidly degraded(2) The tightly associated hydroxyl radicals with the cobalt complex were investigated as the reactive species for AOII degradation in the Co2+-HCO3--H2O2 system. Co2+ can be oxidated to Co3+ firstly, and then partly of the Co3+ can be reduced to Co2+.(3) It can be concluded that the contemporaneous cleavage of the two C-N bonds of AOII by the Co2+-HCO3--H2O2 system led to decolorization of the dye with the formation N2,p-PSA and 1,2-naphthaquinone, a possible pathway of dye degradation was proposed in details.(4) Cu2+-HCO3--H2O2 was also proved to be an effective system for the degradation of the AOII as well as MO, MR and TB. The formed copper (II) species at different HCO3- concentrations were calculated. The study of the interaction among the Cu2+-HCO3--H2O2 system indicated that Cu2+ can form different complexes with HCO3- showed a new absorption peak at 270nm in the UV area.(5) The radical scavenging measurements further implied that the produced higher oxidation state of copper, Cu (Ⅲ) was to be responsible for the dye decolorization. With the addition of H2O2, the valence of Cu2+ was supposed to change in the Cu2+-HCO3-solution, the amount of formed Cu(Ⅲ) within 60min was suggested to be 13% according to the amount calculation of Cu(Ⅰ) and Cu(Ⅱ). The contemporaneous cleavage of the two C-N bonds of AOII by the Cu2+-HCO3--H2O2 system led to dye degradation with the formation of N2, p-PSA,1,2-naphthaquinone and its further oxidation product.(6) The kinetics studies of formed Cu(Ⅰ) was also investigated. It shows that the higher concentrations of hydrogen peroxide, the higher rate of the reactions. But when it comes to 50mM, the rate almost does not increase. For the different concentration of sodium bicarbonate, it first increased and then decreased with the maximum value obtained at 5mM HCO3-.更多还原