非晶合金降解偶氮染料的性能研究
发布时间：2018-09-10 13:45
【摘要】：近期,研究发现非晶合金能高效降解偶氮染料分子,受到了广泛的关注。该发现为非晶合金作为功能材料的应用开辟了新的方向。然而,关于非晶合金对偶氮染料高效降解机理、非晶合金的成分和表面状态等对降解行为的影响规律及机制等问题的理解尚不深入,影响了适用于高效降解印染废水的非晶合金成分及工艺的发展。针对此,本文开展了 Fe基非晶合金、Co基非晶合金和Cu基非晶合金对偶氮染料降解行为及机制的研究,同时研究了 Fe基非晶合金与电化学方法耦合降解偶氮染料的行为及机制。研究结果一方面加深了非晶合金高效降解偶氮染料的行为及机制的理解,另一方面对发展高性能水处理用非晶合金及其实际应用具有重要的推动作用。表面氧化的Fe_(78)Si_8B_(14)非晶合金对偶氮染料溶液的脱色过程可以分为两个阶段,且均符合假一级衰减动力学模型。第一阶段主要表现为对染料分子的吸附效应,第二阶段表现为非晶合金对染料分子还原、催化降解过程。脱色速率第二阶段优于第一阶段。这种降解行为主要与表面氧化的Fe_(78)Si_8B_(14)非晶合金在偶氮染料水溶液中的表面组织状态演变密切相关。在偶氮染料水溶液中,Fe基非晶合金的表面氧化膜首先溶解破裂,暴露出新鲜表面,进一步被腐蚀,逐渐形成疏松状表面组织,一方面有利于对染料分子的吸附,另一方面,随着吸附染料分子的量增多,暴露的新鲜表面能够充分接触到染料分子,从而诱发了还原反应、催化降解等过程的发生。连续多次重复降解试验也验证了这一点。除首次外,其余各次的脱色过程均为一步反应,并具有更快的脱色效率。由此可见,表面氧化膜只在一定程度上延缓了脱色进程,而对Fe_(78)Si_8B_(14)非晶合金降解偶氮染料的最终效果及长久使用性能影响不大。Co78Si8B14非晶合金具有很好的降解偶氮染料能力,其降解偶氮染料的速率高于相应的晶态合金以及Fe基、Mg基非晶合金,同时表现出较小的质量损失。这主要是由于Co0作为电子提供者还原降解染料分子的作用较弱,而Co78Si8B14非晶合金中高度配位不饱和的原子作为催化剂,利用吸附的原子态氢对染料分子进行加氢催化,以及Si、B和Co之间形成局部电偶,电催化水与溶解氧反应生成强氧化性的·OH氧化分解偶氮染料起主导作用。这种降解机制使得Co78Si88B14非晶合金降解偶氮染料的适用范围更宽,对于不同温度、不同初始浓度、不同pH (3～10)的染料废水都能实现很好的降解效果,且能多次重复使用。Cu46Zr445A175Gd2非晶合金也能够很好地降解偶氮染料,降解反应的表观激活能仅为17 kJ/mol,远低于已有非晶合金降解偶氮染料的表观激活能,说明Cu46Zr44.5A17 5Gd2非晶合金降解偶氮染料时具有高催化活性。此外,Cu46Zr44.5A17.5Gd2非晶合金具有优异的耐腐蚀性能,其在降解偶氮染料的过程中几乎没有腐蚀损耗以及零价金属还原偶氮染料的反应,使得Cu46Zr44 5A175Gd2非晶合金在降解偶氮染料的过程具有良好的稳定性,如在重复循环使用十次之后,Cu46Zr44.5A17.5Gd2非晶合金处理偶氮染料的降解效率和降解速率依然能够保持不变。相对于Fe基、Mg基和Co基等非晶合金,Cu46Zr44 5A175Gd2非晶合金降解染料废水不仅速率快,使用寿命更是大幅度提高,但pH值适用范围相对较小。电场的施加对于Fe_(78)Si_8B_(14)非晶合金降解偶氮染料具有重要促进作用。Fe_(78)Si_8B_(14)非晶合金与电化学方法联用,能够电催化H2O与O2反应生成羟基自由基(·OH),从而快速氧化染料分子,提高降解速率。U=1 V时Fe_(78)Si_8B_(14)非晶合金电化学的降解偶氮染料的反应速率比U=0 V的化学法快12倍。Fe_(78)Si_8B_(14)非晶合金电化学降解偶氮染料的电能耗和电极质量损失均较小。与形稳阳极、硼掺杂金刚石膜电极和炭电极等相比,Fe_(78)Si_8B_(14)非晶合金条带作为电极电化学降解染料废水的单位电能耗降低了 4～6个数量级,这解决了电化学处理染料废水技术中的一大难题,极大促进了电化学处理废水技术的实施。
[Abstract]:Recently, the discovery that amorphous alloys can degrade azo dye molecules efficiently has attracted wide attention. This discovery opens up a new direction for the application of amorphous alloys as functional materials. However, the mechanism of high-efficiency degradation of azo dyes by amorphous alloys, the influence of composition and surface state of amorphous alloys on the degradation behavior and the mechanism are also discussed. Understanding of the problem of fabrication is not thorough, which affects the development of amorphous alloy composition and technology for efficient degradation of printing and dyeing wastewater. In this paper, the degradation behavior and mechanism of azo dyes by Fe-based amorphous alloys, Co-based amorphous alloys and Cu-based amorphous alloys are studied, and the coupling between Fe-based amorphous alloys and electrochemical methods is also studied. Behavior and mechanism of azo dye degradation by combination. The results of this study not only deepen the understanding of the behavior and mechanism of azo dye degradation by amorphous alloys, but also promote the development of amorphous alloys for high performance water treatment and their practical applications. The decolorization process can be divided into two stages, which are in accordance with the pseudo-first-order decay kinetic model. The first stage is mainly the adsorption of dye molecules, the second stage is the reduction of dye molecules by amorphous alloys and the catalytic degradation process. In Azo Dye Aqueous solution, the surface oxide film of Fe-based amorphous alloy first dissolves and breaks down, exposes the fresh surface, further corrodes, and gradually forms loose surface structure. On the one hand, it is beneficial to the adsorption of dye molecules. On the other hand, with the increase of the amount of adsorbed dye molecules, the exposed fresh surface can fully contact the dye molecules, which induces the reduction reaction, catalytic degradation and other processes. It can be seen that the surface oxidation film only delays the decolorization process to a certain extent, but has little effect on the final effect of degradation of azo dyes and long-term performance of Fe_ (78) Si_8B_ (14) amorphous alloy. Co78Si8B14 amorphous alloy has a good ability to degrade azo dyes, and its degradation rate of azo dyes is higher than that of corresponding crystalline alloy. This is mainly due to the weak role of Co0 as an electron provider in reducing and degrading dye molecules, whereas the highly coordinated unsaturated atoms in Co78Si8B14 amorphous alloy act as catalysts for hydrogenation of dye molecules by adsorbed atomic hydrogen, and Si, B and Co. The degradation mechanism makes the amorphous alloy Co78Si88B14 more suitable for the degradation of azo dyes. The dye wastewater with different initial pH (3-10) can be achieved at different temperatures and concentrations. Cu46Zr445A175Gd2 amorphous alloy can also degrade azo dyes well. The apparent activation energy of the degradation reaction is only 17 kJ/mol, which is much lower than the apparent activation energy of the existing amorphous alloy degrading azo dyes. Cu46Zr44.5A17.5Gd2 amorphous alloys have excellent corrosion resistance, almost no corrosion loss and zero-valent metal reduction of azo dyes during the degradation of azo dyes. Cu46Zr44.5A175Gd2 amorphous alloys have good stability in the degradation of azo dyes. For example, Cu46Zr44.5A175Gd2 amorphous alloys can be reused for ten times. Compared with Fe-based, Mg-based and Co-based amorphous alloys, Cu46Zr44 5A175Gd2 amorphous alloys can degrade dye wastewater at a faster rate and a longer service life, but the pH value is relatively small. Fe_ (78) Si_8B_ (14) amorphous alloy can electrocatalyze the reaction of H2O with O2 to form hydroxyl radical (. OH), thus rapidly oxidizing the dye molecule and increasing the degradation rate. The reaction rate is 12 times faster than that of U=0 V chemical method. The energy consumption and electrode mass loss of Fe_ (78) Si_8B_ (14) amorphous alloy for electrochemical degradation of azo dyes are small. Compared with shape stabilized anode, boron doped diamond film electrode and carbon electrode, Fe_ (78) Si_8B_ (14) amorphous alloy strip is used as electrode for electrochemical degradation of dye wastewater. The reduction of 4-6 orders of magnitude has solved a difficult problem in the electrochemical treatment of dye wastewater and greatly promoted the implementation of the electrochemical treatment of wastewater technology.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X703;TG139.8
本文编号：2234615
[Abstract]:Recently, the discovery that amorphous alloys can degrade azo dye molecules efficiently has attracted wide attention. This discovery opens up a new direction for the application of amorphous alloys as functional materials. However, the mechanism of high-efficiency degradation of azo dyes by amorphous alloys, the influence of composition and surface state of amorphous alloys on the degradation behavior and the mechanism are also discussed. Understanding of the problem of fabrication is not thorough, which affects the development of amorphous alloy composition and technology for efficient degradation of printing and dyeing wastewater. In this paper, the degradation behavior and mechanism of azo dyes by Fe-based amorphous alloys, Co-based amorphous alloys and Cu-based amorphous alloys are studied, and the coupling between Fe-based amorphous alloys and electrochemical methods is also studied. Behavior and mechanism of azo dye degradation by combination. The results of this study not only deepen the understanding of the behavior and mechanism of azo dye degradation by amorphous alloys, but also promote the development of amorphous alloys for high performance water treatment and their practical applications. The decolorization process can be divided into two stages, which are in accordance with the pseudo-first-order decay kinetic model. The first stage is mainly the adsorption of dye molecules, the second stage is the reduction of dye molecules by amorphous alloys and the catalytic degradation process. In Azo Dye Aqueous solution, the surface oxide film of Fe-based amorphous alloy first dissolves and breaks down, exposes the fresh surface, further corrodes, and gradually forms loose surface structure. On the one hand, it is beneficial to the adsorption of dye molecules. On the other hand, with the increase of the amount of adsorbed dye molecules, the exposed fresh surface can fully contact the dye molecules, which induces the reduction reaction, catalytic degradation and other processes. It can be seen that the surface oxidation film only delays the decolorization process to a certain extent, but has little effect on the final effect of degradation of azo dyes and long-term performance of Fe_ (78) Si_8B_ (14) amorphous alloy. Co78Si8B14 amorphous alloy has a good ability to degrade azo dyes, and its degradation rate of azo dyes is higher than that of corresponding crystalline alloy. This is mainly due to the weak role of Co0 as an electron provider in reducing and degrading dye molecules, whereas the highly coordinated unsaturated atoms in Co78Si8B14 amorphous alloy act as catalysts for hydrogenation of dye molecules by adsorbed atomic hydrogen, and Si, B and Co. The degradation mechanism makes the amorphous alloy Co78Si88B14 more suitable for the degradation of azo dyes. The dye wastewater with different initial pH (3-10) can be achieved at different temperatures and concentrations. Cu46Zr445A175Gd2 amorphous alloy can also degrade azo dyes well. The apparent activation energy of the degradation reaction is only 17 kJ/mol, which is much lower than the apparent activation energy of the existing amorphous alloy degrading azo dyes. Cu46Zr44.5A17.5Gd2 amorphous alloys have excellent corrosion resistance, almost no corrosion loss and zero-valent metal reduction of azo dyes during the degradation of azo dyes. Cu46Zr44.5A175Gd2 amorphous alloys have good stability in the degradation of azo dyes. For example, Cu46Zr44.5A175Gd2 amorphous alloys can be reused for ten times. Compared with Fe-based, Mg-based and Co-based amorphous alloys, Cu46Zr44 5A175Gd2 amorphous alloys can degrade dye wastewater at a faster rate and a longer service life, but the pH value is relatively small. Fe_ (78) Si_8B_ (14) amorphous alloy can electrocatalyze the reaction of H2O with O2 to form hydroxyl radical (. OH), thus rapidly oxidizing the dye molecule and increasing the degradation rate. The reaction rate is 12 times faster than that of U=0 V chemical method. The energy consumption and electrode mass loss of Fe_ (78) Si_8B_ (14) amorphous alloy for electrochemical degradation of azo dyes are small. Compared with shape stabilized anode, boron doped diamond film electrode and carbon electrode, Fe_ (78) Si_8B_ (14) amorphous alloy strip is used as electrode for electrochemical degradation of dye wastewater. The reduction of 4-6 orders of magnitude has solved a difficult problem in the electrochemical treatment of dye wastewater and greatly promoted the implementation of the electrochemical treatment of wastewater technology.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X703;TG139.8
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