【作者】 赵雷；

【导师】 马军；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2008， 博士

【摘要】 随着工业的迅猛发展和人类物质生活水平的提高,水环境污染已是普遍存在的问题,饮用水的卫生和安全也受到越来越多的关注。然而,城市给水常规处理工艺对于近年来微污染水源水中出现的一些有机污染物的处理能力有限,很难将其降解。使用非均相催化剂来提高臭氧氧化能力的高级氧化技术,因其工艺简单、易于回收处理、水处理成本较低、活性高等优点,得到了研究者的普遍重视。本文研发的超声强化蜂窝陶瓷催化臭氧化去除水中有机物的高级氧化技术,实现了超声降解与非均相催化臭氧化的有机结合,产生的协同效应使得蜂窝陶瓷催化臭氧化工艺在有效且方便的前提下进一步提高了氧化降解效能和催化剂的使用寿命,同时也弥补了单独声解水中污染物历时长、费用高、降解效率低等局限性,提高了声能的利用率和有机物的降解速度与程度。超声强化蜂窝陶瓷催化臭氧化工艺对水中硝基苯的降解效果随着单场频率的升高（20⁴0kHz）而增加。三个不同频率的垂直正交的超声场对水中硝基苯降解的强化效果最好,频率相差越大,强化效果越明显。超声/臭氧/蜂窝陶瓷组合工艺具有明显的协同效应,显著提高了水中硝基苯的降解效能。臭氧作为空化气体对组合工艺去除水中硝基苯具有最好的强化效能,且臭氧投量和气体流速与硝基苯的降解效能均成正相关性,连续投加可以明显获得优于一次性投加的去除效果。超声/臭氧/蜂窝陶瓷组合工艺对水中硝基苯的降解效能分别随着水体温度、初始pH值、水体循环流速、蜂窝陶瓷催化剂的用量和孔密度、硝基苯初始浓度和声强的升高而增加,均成正相关性。且降解效能按照混凝江水、自来水、沉后水、蒸馏水和超纯水的顺序呈现降低趋势。水中常见无机金属阳离子(Na⁺、K⁺、Ag⁺、Mg²⁺、Ca²⁺、Ba²⁺、Mn²⁺、Fe²⁺、Co²⁺、Ni²⁺、Cu²⁺、Zn²⁺、Cd²⁺、Cr³⁺、Fe³⁺和Al³⁺)和阴离子(NO₃^- ,Cl^- ,HCO₃^-、H₂PO₄^―、SO₄^2―、CO₃^2―、HPO₄^2―和PO₄^3―)对各个体系去除水中硝基苯降解效能的影响比较复杂,分别表现出了无影响、促进、先促进后抑制和抑制作用。水中常见有机物甲醛和邻苯二甲酸二丁酯可以抑制超声/臭氧/蜂窝陶瓷对水中硝基苯的降解,腐殖酸、甲醇和甲酸分别使得硝基苯的降解都经历了先促进后抑制的过程。蜂窝陶瓷催化剂的主晶相为2MgO·2Al₂O₃·5SiO₂,是标准的α-堇青石结构;催化剂的表面存在着表面羟基,其含量为9.13×10^-6mol^·m^-2;催化剂表面的pHZPC为6.60。超声或/和蜂窝陶瓷催化剂的引入分别促进了体系中臭氧的分解,降低了水中的剩余臭氧浓度,减少了臭氧尾气浓度,提高了体系的臭氧利用率,加速了体系中^·OH和H₂O₂的生成,从而强化了对TOC的矿化能力。且超声/臭氧/蜂窝陶瓷联用具有最好的协同效应。氧化路径分析表明,硝基苯的降解经历了芳环的羟基化、有机氮的矿化、通过开环反应由芳香族化合物向脂肪族化合物的转化及脂肪族链式化合物的氧化;主要的芳香族化合物和有机羧酸等中间产物包括硝基苯酚类、硝基苯多酚类、苯酚、对苯二酚、对苯醌、丙二酸、乙酸、NO₃^-、顺丁烯二酸和草酸,进一步证实硝基苯的降解遵循^·OH氧化机理。超声/臭氧/蜂窝陶瓷对硝基苯的降解符合假一级反应动力学模型,其协同效应反应速率常数为13.62×10^-2min^-1。假一级表观反应速率常数分别与臭氧投量、臭氧气体流速、催化剂用量、催化剂孔密度、反应温度、初始pH值、水体循环流速和声强成正相关性。动力学经验方程式为: -dC/dt=k₀[O₃]^0.98[Cata]^1.61T^0.54（pH）^0.98I^1.90[C]。超声/臭氧/蜂窝陶瓷组合工艺对松花江水源水中TOC、COD_Mn、UV₂₅₄和NO2–-N的去除分别具有明显的协同效应,出水中大分子有机物的含量相对减少,小分子有机物的含量相对增加;出水中有机物的可生化降解性依次提高,体系中最易被细菌吸收、能直接同化成细菌体的有机物部分的含量增加。强化体系也使原水中的NH3-N和NO3–-N的浓度依次增加。超声/臭氧/蜂窝陶瓷工艺处理后可使松花江水源水中152种有机物减少到27种,并且在三致物、美国EPA优先污染物和内分泌干扰物的去除方面具有明显的优势。更多还原

【Abstract】 With the development of industry and the increase of living condition, the pollution of water environment exists wildly. Therefore, the sanitary standards and the security of drinking water have received more and more much attention throughout the world. However, the conventional processes have been shown to achieve a very limited mineralization of organic micropollutants in drinking water treatment. In recent years, heterogeneous catalytic ozonation, as a promising advanced oxidation processes （AOPs）, has been investigated for degrading organic compounds in water treatment due to its high oxidation potential.Ultrasound enhanced ceramic honeycomb catalytic ozonation, as a novel AOP, was invented to decompose organic compounds in water, using a vertical three ultrasonic reactor for the first time. This enhanced process achieved the organic combination of ultrasonic degradation and heterogeneous catalytic ozonation. The synergistic effect of the combined process further improved the degradation efficiency of the ceramic honeycomb catalytic ozonation system based on the advantages of efficiency and convenience, and increased the lifetime of ceramic honeycomb catalyst. Simultaneously, it also could remedy the expensive and ineffective limits of sonolysis alone for the degradation of contaminations in water, enhancing the using efficiency of ultrasonic intensity and the degradation rate of organic compound.The degradation efficiency of nitrobenzene in aqueous solution increased with the increase of single frequency （20⁴0 kHz） in the enhanced process of ceramic honeycomb catalytic ozonation by ultrasound. The enhancement efficiency was even more pronounced in the presence of vertical triple transducers with different frequency. The larger the difference between the frequencies used by the experiment, the higher enhancement efficiency was achieved. The combined process of ultrasound/ozone/ceramic honeycomb presented the obvious synergistic effect for the ozonation of nitrobenzene, resulting in a remarkable improvement of degradation efficiency. The best enhanced efficiency could be obtained when ozone was used as dissolved gas. In addition, total ozone applied and gas flow rate presented respectively the positive correlation with the degradation efficiency of nitrobenzene. With the same dosage of applied ozone, the multiple steps addition of ozone showed the higher degradation efficiency than that obtained by adding within one step before the start of the experiment.The degradation efficiency of nitrobenzene in the combined process increased with the increase of reaction temperature, initial pH, circle flow rate, amount of catalyst, pore density of catalyst, initial concentration of nitrobenzene and ultrasonic intensity, respectively, suggesting the positive correlation. Furthermore, the degradation efficiency of nitrobenzene decreased according to the following rule: flocculated river water, tap water, sedimentated water, distilled water and superpure water. The effects of general inorganic metal ions (Na⁺、K⁺、Ag⁺、Mg²⁺、Ca²⁺、Ba²⁺、Mn²⁺、Fe²⁺、Co²⁺、Ni²⁺、Cu²⁺、Zn²⁺、Cd²⁺、Cr³⁺、Fe³⁺ and Al³⁺) and anions (NO₃^-,Cl^― ,HCO₃^-、H₂PO₄^―、SO₄^2―、CO₃^2―、HPO₄^2― and PO₄^3―) on the degradation efficiency of nitrobenzene were complex in the different processes, representing no remarkable effect, accelerating effect, restraining effect and so on, respectively. Moreover, formaldehyde and dibutyl phthalate could inhibit the degradation of nitrobenzene. The experimental results indicated that humic acid, methanol and formic acid could accelerate the degradation of nitrobenzene at the lower concentration, and the reactions were retarded at higher concentrations.The bulk crystalline phase of ceramic honeycomb catalyst was 2MgO·2Al₂O₃·5SiO₂, which was the standard structure ofα-cordierite. The determination result indicated that the density of surface hydroxyl groups existing on the surface of ceramic honeycomb was 9.13×10^-6mol·m^-2, and the pHPZC was 6.60. The introduction of ultrasound or/and ceramic honeycomb catalyst accelerated the decomposition of ozone, resulting in the concentration decreases of residual ozone and offgas ozone. It also increased the utilization efficiency of ozone, the concentrations of ^·OH and H₂O₂ formation, leading to the improvement of mineralization level of TOC. The synergistic effect was even more pronounced in the combined process of ultrasound/ozone/ceramic honeycomb.The investigation of proposed oxidation pathways suggested that the degradation of nitrobenzene seemed to occur in several steps as follows: the hydroxylation of aromatic ring, the mineralization of organic nitrogen, the transformation of aromatics to aliphatics by destruction of ring structures and the oxidation of the aliphatic chains. The major intermediary degradation products detected in the experiment were nitrophenols, multihydroxy derivatives and low molecular weight organic acids, including nitrophenol isomers of o, p, m-nitrophenol, 4-nitrocatechol, 1,4-dihydroxy-2-nitrobenzene, 3,4,5-trihydroxynitrobenzene, 2,3,5-trihydroxynitrobenzene and 2,3,4,5-tetra-hydroxynitrobenzene. Phenol, hydroquinone, benzoquinone and nitrate ion were also detected as intermediates formation, confirming that ^·OH oxidation was the major reaction pathway in the present catalytic ozonation.The results indicated that degradation of nitrobenzene followed the pseudo-first-order kinetic model, and the rate constant kU-O-C of synergistic effect was 13.62×10^-2min^-1. The pseudo-first-order rate constant exerted the positive correlation with total ozone applied, gas flow rate, amount of catalyst, pore density of catalyst, reaction temperature, initial pH, circle flow rate and ultrasonic intensity, respectively. The kinetic practical equation could be expressed as follows: -dC/dt=k₀[O₃]^0.98[Cata]^1.61T^0.54（pH）^0.98I^1.90[C]The combined process of ultrasound/ozone/ceramic honeycomb presented respectively the obvious synergistic effect for the removal of TOC、COD_Mn、UV₂₅₄ and NO₂^--N from raw water of Songhuajiang River. The proportion of low molecular weight organic compounds in raw water from Songhuajiang River was increased after the treatment by the combined process. Furthermore, the combined process increased the biodegradablility and the assimilable organic carbon （AOC） of raw water, and also increased the concentrations of NH₃-N and NO₃^–-N. The total kinds of organic compounds decreased from 152 of raw water to 27 of treated water by the combined process of ultrasound/ozone/ceramic honeycomb. The experimental results illustrated that the combined process had the remarkable synergistic effect for the removals of“three cause”organic compounds, prior controlled organic compounds of EPA and endocrine disrupting chemicals in raw water from Songhuajiang River.更多还原