【作者】 王梓；

【导师】 童少平；

【作者基本信息】 浙江工业大学 ， 应用化学， 2008， 硕士

【摘要】 本文首先综述了臭氧的物理化学性质和在水处理方面的应用,提出了本论文的研究目的.研究内容主要包括四部分:O₃/UV催化臭氧化降解水中有机物的机理研究;Fe²⁺/Fe³⁺均相催化臭氧化苯酚的研究;MnO₂催化臭氧化降解苯甲酸钠.第三章中,实验研究了O₃/UV催化臭氧化降解水中有机物的机理.初步证实O₃/UV产生HO·的作用机理为:O₃+H2O→H₂O₂+O₂;H₂O₂→2·OH.UV能够促使溶解臭氧产生H₂O₂,进而生成羟基自由基,当对H₂O₂水溶液鼓O₂时,UV对H₂O₂的分解作用明显加快.在O₃/UV降解技术中,当目标有机物是对自由基链反应具有较好促进作用的乙醇酸时,即使是较弱的引发反应,也能使乙醇酸很好地降解;而当目标有机物是对自由基链反应具有抑制作用的乙酸时,引发足够量的羟基自由基（OH-,H₂O₂）是乙酸得到较好降解的必要条件.目标有机物（如芳族类和带不饱和键的化合物）在臭氧化过程中形成中间产物H₂O₂是O₃/UV降解效率提高的关键因素,其直接导致体系形成O₃/H₂O₂和H₂O₂/UV这2种高级氧化技术,从而提高体系产生羟基自由基的效率.第四章的研究结果表明,在一定条件下,在苯酚的臭氧化降解过程中,臭氧分子与苯酚及苯氧负离子的直接反应是苯酚降解的主要原因.Fe²⁺和Fe³⁺对臭氧化降解苯酚均具有催化作用,其中Fe²⁺的催化效果更佳.Fe²⁺催化降解苯酚的机理是:苯酚在臭氧化降解过程中产生了H₂O₂,分别同臭氧和Fe²⁺形成了O₃/H₂O₂和Fenton体系,促进了苯酚的去除.不同体系R_ct的大小:O₃/Fe²⁺＞O₃/Fe³⁺＞_O3.这个结果也与苯酚的降解效果相一致.第五章的研究结果表明,单独使用臭氧降解苯甲酸钠时,虽然在一定条件下苯甲酸钠可以被完全降解,但体系COD仍有较高的残留.加入MnO₂对COD的去除有明显的提高（由原来的79%提高到94%）,显示了较好的催化性能.O₃/MnO₂体系的R_ct大于单独臭氧化.MnO₂催化臭氧化降解苯甲酸钠的机理是:MnO₂和草酸形成了草酸锰复合物,提高了臭氧对小分子有机酸的反应活性,致使反应溶液pH升高,进而加速臭氧分解.通过加入自由基猝灭剂,发现·OH也是提高体系矿化率的重要原因.更多还原

【Abstract】 The physical chemistry properties of ozone and its application in water treatment were reviewed,the research objection was proposed too. There were three parts in this paper:Mechanism of UV catalytic ozonation of organic compound in solution;Fe²⁺/Fe³⁺homogeneous catalytic ozonation of phenol;MnO₂ catalytic ozonation of Sodium Benzoate. In chapterⅢ,the mechanism of producing of OH in O3/UV was proposed as follows:O₃ + H₂O→H₂O₂ + O₂;H₂O₂→2·OH.UV can promote the dissolved ozone to firstly produce H₂O₂,then the intermdiate H₂O₂ can react with dissolved ozone or decompose by UV to produce HO·.The experimental results also indicated that decomposition of H₂O₂ radiated by UV could be accerlated in the present of O₂.Furthermore,the characteristic of organic,which acts as promoter or inhibitor in the process of ozonation, also affects the degradation efficiency of O₃/UV directly,when glycolic acid,a promoter in ozonation,was degraded,the combination UV radiation with ozonation could remove it efficiency despite of less initiation reaction; however,when acetic acid,an inhibitor in ozonation,was degraded by O₃/UV,the removal rate of acetic acid was very low unless enough initiation of hydroxyl radical（OH^-,H₂O₂）.The intermediate H₂O₂,has been proved to plays an important role in enhancement of degradation efficiency of O₃/UV.It resulted directly in the formation of two AOPs:O₃/H₂O₂和H₂O₂/UV systems,which both produce·OH efficiently.The results in chapterⅣshow that the direct reactions between phenol（or C₆H₅O^-）and ozone are the main causes for degradation of phenol.Both Fe²⁺and Fe³⁺could improve the degradation efficiency of ozonation of phenol,and Fe²⁺had higher activity in ozonation of phenol than Fe³⁺had.The possible mechanism of Fe²⁺homogeneous catalytic ozonation of phenol includes two reasons:O₃/H₂O₂ and Fenton system.In this system,the intermdiate H₂O₂ resulted in promoting the removal of phenol.The R_ctof different systems is:O₃/Fe²⁺＞O₃/Fe³⁺＞O₃,which is in accordance with their degradaton efficiencies of phenol.The results in chapterⅤshow that the COD removal was not high in spite of the complete disappearance of Sodium Benzoate in specific time,indicating some compounds inert to ozone accumulated in solution. Addition of MnO₂ increased the degradation efficiency of COD by ozone obviously（from 79%to 94%）.R_ctof different systems were calculated: O₃/MnO₂＞O₃.The mechanism of MnO₂ catalytic ozonation of Sodium Benzoate included two causes:（1）MnO₂ increased the reactive activity of organic acid with ozone;（2）adding MnO₂ cound increase the pH of solution,then high pH promoted the decomposition of ozone to produce·OH.The radical scavenger test confirmed the second cause.更多还原