【作者】 齐飞；

【导师】 陈忠林；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2008， 博士

【摘要】 嗅味问题(taste and odor problem)是饮用水处理技术领域面临的全球性问题。水库水和湖泊水的富营养化使得此类水为水源的饮用水嗅味问题尤为突出。常规的饮用水处理技术在解决水体嗅味问题方面能力十分有限。目前国内外虽然已经采取一些强化去除技术解决饮用水中嗅味问题,但这些技术均存在一定问题,如强化去除能力微弱,氧化剂剩余问题和工艺造价问题等。因此开发新型的饮用水深度处理技术,解决饮用水嗅味问题是十分必要的。本文在深入分析臭氧氧化技术在解决水体嗅味问题方面存在问题的基础上,采用γ-Al2O3催化臭氧氧化技术去除水体中嗅味物质2-甲基异莰醇(2-Methylisoborneol, MIB);为了探求铝氧化物在催化臭氧氧化过程中的催化机理,以典型铝氧化物(γ-AlOOH,γ-Al2O3,α-Al2O3)为例,研究了铝氧化物催化臭氧分解规律;采用不同化学结构的嗅味物质为目标物,讨论了铝氧化物催化臭氧氧化嗅味物质的反应机理;采用天然铝矾土为原料,经过简单热处理过程,制备出具备去除不同化学结构嗅味物质能力的高效催化剂。首先以典型嗅味物质MIB为代表,研究了臭氧氧化技术对MIB的降解能力和氧化机理,并深入分析臭氧氧化技术在去除水体嗅味方面存在的问题。通过对溶液pH和羟基自由基抑制剂对MIB氧化过程的影响,提出在臭氧氧化MIB的过程中(中性条件下),分子臭氧和羟基自由基起到协同氧化作用。通过对氧化后样品进行气质联机分析,提出d-樟脑是臭氧氧化MIB过程中的主要中间产物,推测出臭氧氧化MIB的降解途径。根据对臭氧氧化MIB效能和机理的研究结果,认为常规臭氧投量下,臭氧氧化技术不能彻底解决水体嗅味问题。以典型嗅味物质MIB为代表,深入研究了γ-Al2O3催化臭氧氧化MIB的降解效能和机理,考察γ-Al2O3催化臭氧氧化技术解决水体嗅味问题的能力。γ-Al2O3的加入显著强化了臭氧对MIB的氧化能力。通过自由基抑制实验和ESR分析,证明羟基自由基是γ-Al2O3催化臭氧氧化过程产生的重要活性物种,并对催化臭氧氧化过程中羟基自由基产率进行测定。通过研究溶液pH值和络合性阴离子对γ-Al2O3催化臭氧氧化MIB能力的影响,证明附着在γ-Al2O3表面的羟基是催化臭氧氧化MIB反应中的活性位。为了探求铝氧化物在催化臭氧氧化过程中的催化机理,以典型铝氧化物(γ-AlOOH,γ-Al2O3,α-Al2O3)为例,研究了典型铝氧化物催化臭氧分解的规律,针对铝氧化物催化臭氧分解机理进行探讨。铝氧化物均可以强化臭氧分解。以羟基自由基抑制实验和羟基自由基产率为表示方法,证明了铝氧化物可以催化臭氧分解,并可以提高羟基自由基产率。根据溶液pH值和络合性无机阴离子对铝氧化物催化臭氧分解能力的影响,证明表面羟基是催化臭氧分解反应的活性位。同时铝氧化物表面的Br?nsted酸性同其催化臭氧分解能力密切相关。将典型铝氧化物应用于去除嗅味物质MIB和2,4,6-三氯苯甲醚(2,4,6-Trichloroaminsole, TCA)的过程中,探讨不同结构和表面性质的铝氧化物在催化臭氧氧化过程中的作用和行为。通过对催化臭氧氧化过程中氧化剂贡献进行计算可知,在催化臭氧氧化MIB过程中,具有最高催化活性的γ-Al2O3主要以·OH氧化反应为主;催化活性最弱的γ-AlOOH,是以分子臭氧为主的氧化过程。在三种铝氧化物催化臭氧氧化TCA的过程中,主要以·OH的氧化过程为主。通过研究溶液pH值对催化反应的影响,证明了表面羟基是催化臭氧氧化有机物的表面活性位。通过研究铝氧化物对MIB和TCA的吸附作用,得出通过与表面羟基的作用,MIB吸附在铝氧化物表面,而TCA是物理性的吸附在氧化物表面。由于表面羟基既是γ-AlOOH吸附MIB的吸附位,同时也是催化臭氧分解产生羟基自由基的活性位,推测MIB在γ-AlOOH表面的吸附,抑制了γ-AlOOH催化臭氧分解产生·OH的能力。根据铝氧化物表面性质和有机物在其表面吸附行为在催化反应中的作用,提出铝氧化物催化臭氧氧化MIB和TCA的催化反应途径。采用廉价的天然铝矾土为原料,进行简单的热处理,制备了其具有γ-AlOOH和γ-Al2O3双重的表面性质的催化剂。在催化臭氧氧化不同结构的嗅味物质过程中均表现出显著的催化活性。通过自由基抑制实验和羟基自由基产率的计算,证明热处理后的铝矾土可以促进臭氧分解,提高羟基自由基产率。更多还原

【Abstract】 Taste and odor (T&O) problem is a key problem of drinking water treatment allover the world. Eutrophication of reservoir water and lake water has made the T&O problem more serious. At the same time, traditional drinking water treatment is not efficient for solving T&O problem. Though many strategies of drinking water treatment have been carried out to solve T&O problem, there are still many blemishes for application in water treatment, such as weak removal efficiency, residual oxidant, and higher cost. So exploring new advanced drinking water treatment for resolving T&O problem is very important.Due to problems emerged in resolving water taste and odor problems by ozonation, invesgitation ofγ-Al2O3 catalyzed ozonation for 2-methylisoborneol, (MIB) removal was carried out. Then, takenγ-AlOOH,γ-Al2O3, andα-Al2O3 as catalysts, the rule of aluminum oxides catalyzed ozone decomposition was investigated. By choosing MIB and 2,4,6-Trichloroaminsole (TCA) as the target compounds, the mechanism of aluminum oxide catalyzed ozonation was discussed. Finally, using natural bauxite as raw material, the catalyst which was efficient to remove both MIB and TCA was prepared through a simple heat treatment.Removal efficiency and mechanism of MIB by ozonation was investigated. Disadvantageous of ozonation MIB was investigated widely. Both ozone molecule and hydroxyl radicals were account for MIB degradation. By GC-MS analysis, it was speculated that d-camphor was a main product of ozonation MIB. A speculated degredation pathway was presumed. On the basis of efficiency and mechanism investigation, there were some problems in ozonation process for MIB degradation.The efficiency and the mechanism of catalyzed ozonation MIB in present ofγ-Al2O3 were carried out. The efficiency of removal MIB was enhanced remarkably byγ-Al2O3. According to inhibiting experiment and ESP analysis, it was specluted that hydroxyl radicals was the acitivity species. Yield of hydroxyl radicals was much higher than that of ozonation alone. Effect of solution pH and anions confirmed surface hydroxyl groups was the activity site for catalyzed ozonation withinγ-Al2O3. To discussing the mechanism of catalyzed ozonation within aluminum oxides, experiments of aluminum oxides (γ-AlOOH,γ-Al2O3,α-Al2O3) catalyzed ozone decomposition were carried out. Aluminum oxides could enhance ozone decomposition. Based on inhibit of hydroxyl radicals experiments and yield of hydroxyl radical, aluminum oxide could enhance ozone decomposition to form hydroxyl radicals. According to effect of solution pH and anion adsorption on catalyzed ozonation, it was confirmed that surface hydroxyl groups was the active site. Br?nsted acidity of aluminum oxide was relationship with catalyzed ozone decomposion.Role of aluminum oxide catalyzed ozonation for MIB and TCA was investigated. Effects of crystal and surface property of aluminum oxide on catalyzed ozonation MIB and TCA were discussed. Efficiency of three aluminum oxides catalyzed ozonation was different. On the basis of quantitative analysis oxidant contribution in catalyzed ozonation, formation of hydroxyl radicals was account for highest catalytic activity ofγ-Al2O3 in oxidation MIB, ozone molecule oxidation was account for lowest catalytic activity ofγ-AlOOH. In the processes of catalyzed ozonation TCA, oxidation of hydroxyl radicals was account for TCA degradation. According to effect of solution pH on catalyzed ozonation, it was confirmed that surface hydroxyl groups was the catalytic active site. Adsorption actions of T&O compounds on aluminum oxides were investigated. It was concluded that MIB was adsorbed on aluminum oxides by surface hydroxyl radical, and TCA was adsorbed on aluminum oxides by physical adsorption. Surface hydroxyl groups was not only the activity site for adsorption of MIB onγ-AlOOH, but also the catatic acitivity site for degradation MIB by catalyzed ozonation process in present of aluminum oxides. Adsorption actions of MIB onγ-AlOOH inhibited the catalytic activity in catalyzed ozonation process.Simple thermal treatment for origin bauxite, made origin materal possessed surface properties of bothγ-AlOOH andγ-Al2O3. Bauxite450 exhibited remarkable catalytic activity in degradation MIB and TCA. By inhibiting experiments of hydroxyl radicals and Rct quantitative determination, Bauxite450 catalytzed ozone decomposition and enhanced field of hydroxyl radicals.更多还原