【作者】 汪恂；

【导师】 龚文琪；

【作者基本信息】 武汉理工大学 ， 矿物加工工程， 2008， 博士

【摘要】 世界范围内生态环保意识的不断加强及传统材料的日益匮乏,为抗菌材料的研究提供了社会背景和生态意义。复合纳米TiO₂这类生态环保抗菌材料是当前研究的热点之一。它不仅可以解决TiO₂的分散与固定化问题,而且通过载体的吸附作用可以在催化剂表面区域形成反应物的富集,促进传质过程,从而提高光催化反应的效率。本文的研究内容主要包括三个部分:（1）金属掺杂玻璃基纳米TiO₂膜的制备、合成、表征及评价;（2）通过含偶氮染料云母珠光颜料工业废水的光催化降解,探索玻璃基纳米TiO₂膜的制备条件并对其光催化氧化性能进行评价;（3）改性TiO₂膜的光催化灭菌研究。文中系统研究了制备玻璃基纳米TiO₂膜的基础性问题;探索并优化在基材表面制备纳米TiO₂膜的工艺条件;重点研究了主要因素影响玻璃基纳米TiO₂晶体结构的规律;分析了掺杂合成的微观机制和界面、表面反应机理;利用TiO₂光催化降解偶氮废水研究影响TiO₂活性的制备条件;探讨了TiO₂膜的光催化杀灭细菌机理;首次利用TEM对古菌光催化杀灭过程进行表征。分析了古菌的结构及光催化灭菌的反应历程。具体的研究内容如下:一、玻璃基纳米TiO₂晶体膜的制备、表征及性能1.系统地考察了影响玻璃基纳米二氧化钛光催化活性的诸因素。重点研究了前躯体配比、干燥温度、煅烧温度、煅烧时间及镀膜次数等因素对玻璃基二氧化钛晶相结构及光催化活性的影响。2.通过实验分析,采用溶胶—凝胶法制备出纯二氧化钛和掺铁、掺铈二氧化钛溶胶,镀膜于载玻片上,解决了以往纳米二氧化钛光催化剂难以回收的问题。3.通过实验确定影响制备玻璃基纳米TiO₂的因素主次顺序为:前驱体配比>煅烧温度>煅烧时间>溶胶反应温度。Ti（OC₄H₉）₄:C₂H₅OH:HNO₃:H₂O=1:15:0.35:2;煅烧时间为2.0h;煅烧温度为450℃;溶胶反应温度为40℃。选择镀膜次数为2次。煅烧温度450℃是玻璃基材表面锐钛矿二氧化钛晶相最稳定的生成温度。二、金属掺杂玻璃基纳米TiO₂晶体膜的合成、表征及评价1.为验证光催化材料扩大光谱可利用范围,研究了光激发源由紫外光延至可见光的可能性和效果。2.采用XRD、UV-Vis、HRTEM等技术对玻璃基掺杂金属离子纳米TiO₂光催化材料的晶体结构、分子结构、表面化学元素组成及化学状态、纳米TiO₂晶体膜进行综合表征分析。三、含偶氮染料云母珠光颜料工业废水的光催化降解1.研究了一种反应速度快、降解脱色率高的催化降解工艺方法,使光催化研究取得了新的进展。2.二氧化钛光催化降解偶氮染料的反应机理是:TiO₂光催化氧化降解偶氮染料的过程是一个首先破坏C-O-C、C-C键,而后N=N双键断开的过程。四、改性TiO₂膜的光催化灭菌作用1.针对改性TiO₂膜的光催化灭菌效率进行了研究:以革兰氏阳性及阴性代表菌种和枯草芽孢杆菌为研究对象,利用电镜表征细菌细胞形态的变化情况,同时采用平板计数法评估改性TiO₂膜的杀菌效果。研究结果表明,改性TiO₂膜杀菌效率明显高于纯TiO₂膜。如Fe³⁺掺杂使TiO₂膜的大肠杆菌杀菌率由87.4%提高至95.8%,金黄葡萄球菌杀菌率由79.4%提高至88.3%,枯草芽孢杆菌杀菌率由80.4%提高至86.3%。Ce⁴⁺的掺杂使TiO₂膜的大肠杆菌杀菌率由87.4%提高至92.7%,金黄葡萄球菌杀菌率由79.4%提高至94.3%,枯草芽孢杆菌杀菌率由80.4%提高至87.7%。由此可知,一定比例的金属掺杂可提高TiO₂膜的杀菌效果。2.首次对微生物三域中的古菌进行了光催化灭菌研究。采用365nm、310nm紫外线反应时间40分钟可杀死绝大多数古菌。含Fe³⁺-TiO₂膜的杀菌作用优于纯TiO₂膜,J7菌杀菌率由88.6%提高至94.5%,同等情况310nm紫外线杀菌率从90.7%提高至93.5%。同样含Ce⁴⁺-TiO₂膜的杀菌作用优于纯TiO₂膜,J7菌杀菌率由88.6%提高至95.3%,同等情况310nm杀菌率由88.7%提高至94.8%。3.本文首次探讨了不同TiO₂膜对古菌的光催化杀灭机理。在紫外线的照射下,TiO₂生成·OH自由基和H₂O₂。依赖于细胞膜上独特的Na⁺-K⁺交换体系,J7嗜盐古菌能够在高盐环境下生存。古菌借助于该体系迅速外排Na+离子,从而使胞内Na⁺离子浓度维持在正常范围。在TiO₂光催化剂与古菌反应时,外排的大量Na⁺离子可能会与Ti键产生相斥作用,使羟基自由基（·OH）与活性氧类物质通过破坏菌壁杀伤J7嗜盐古菌的效能下降。而H202的穿透性强,能够进入古菌细胞导致菌内蛋白质变性分解,DNA分子发生断裂。由此可知,TiO₂主要是通过破坏古菌内部结构及导致K⁺离子的大量泄露致使古菌死亡。4.目前,TiO₂灭菌研究仅限于细菌域与真核生物域。本文首次利用透射电子显微镜（Transmission Electron Microscope,TEM）对古菌死亡过程进行了表征,填补了TiO₂灭菌研究从未涉及古菌域的空白。同时通过探讨古菌的灭菌机理,为深入揭示古菌与其它两域生命形式之间的进化关系提供了新的思路。更多还原

【Abstract】 The worldwide continually strengthened consciousness of environmental protection and more and more scarcity of traditional materials provide the social background and the ecology significance for researches on antibacterial materials. Research on the composition of nano titanium dioxide materials is one of the hotspots of current this kinds of materials researches. Not only it can solves TiO₂ dispersion and immobilized, but also improves the efficiency of the photocatalytic reaction.This dissertation be divided into three parts: （1） Preparation, characterizations and performances study of glass substrate titanium dioxide （Fe-TiO₂ or Ce-TiO₂） film. （2） Study on application and its mechanism of photocatalyitc degradation of AZO-dye wastewater by TiO₂/Fe-TiO₂ or Ce-TiO₂ film. （3） Study on application and its mechanism of photocatalyitc degradation of bactericidal activity. In this paper, some fundamental issues about the preparation of TiO₂/Fe-TiO₂ or Ce-TiO₂ were systematically studied. Conditions in the process of preparation of glass substrate titania film were explored and optimized. The main factors that affect TiO₂ crystal were emphatically studied. Microcosmic mechanism about doping and interface and surface reaction mechanism were analyzed. An analysis of the molecular structure of bacteria and photocatalytic degradation of the reaction course were studied. Study on application of photocatalyitc degradation of AZO-dye wastewater by TiO₂ film , Study on application and its mechanism of sterilization of Gram-negative bacterium、Gram-positive bacterium and Halophilic archaeon by TiO₂ film. TEM analyses were firstly conducted for observation of Halophilic archaeon cell ultrastructure. Conclusions from this study are as follows:1.Preparation, characterizations and performances study of glass substrate titanium dioxide film1.Many factors that affect nano-TiO₂/glass photocatalytic active were inspected comprehensively and systematically. Factors that affect crystal phase and structure and photocatalytic activity of TiO₂ such as: component ratio of precursor, mineral slurry concentration, hydrolysis temperature and time, drying temperature, calcination temperature and time and coating times, etc were emphatically studied.2.Through experiment, TiO₂ thin films were prepared on soda-lime glass by sol-gel method. Those have solved the uses of conventional powder catalysts results in disadvantages in recycle and separation.3.The optimized process conditions of preparation are as follows: volume ratio of precursor: Ti（OC₄H₉）₄: C₂H₅OH: HNO₃:H₂O=1:15: 0.35: 2; hydrolyzed at 40℃; calcined at 450℃for 2h.Among these factors, component ratio of precursor and calcination temperature are considered to be two most remarkables. Preparation confirmed through experiments impact glass nano-TiO₂ order of the primary and secondary factors: Precursor ratio> calcination temperature> calcination time> Sol reaction temperature. The anatase TiO₂ on the surface of glass is moststable when calcined at450℃.2.Preparation, characterizations and performances study of metal ions doped glass substrate titanium dioxide film1. Giving the verification of photocatalytic materials to expand the use of the spectrum , UV excitation extend the possibilities and visible results were be studied.2. XRD, UV-Vis, HRTEM etc techniques were firstly adopted to characteriztions and analyze characteristics of TiO₂/glass doped with metal ion such as: crystal structure, molecular structure, chemical elements and chemical states on the surface, distribution of TiO₂ crystal and thickness of TiO₂ crystal film.3. Study on application and its mechanism of photocatalyitc degradation of AZO-dye wastewater by TiO₂/Fe-TiO₂ or Ce-TiO₂ film.1. A photocatalytic degradation technique has been studied which can speeds-up the reaction and enhances decoloring rate.2. The course of TiO₂ photocatalytic degradation of AZO-dye is the one that C-O-C, C-C bond and then N=N rupture.4. Effects of metal ions-doping TiO₂ film on sterilization（various bacterial and Halophilic archaeon） efficiency1) Experiments were conducted for exploring the efficiency of photocatalytic sterilization of modified TiO₂ films on Escherichia coli, a typical Gram-negative bacterium, and Staphyloccocus aureus Rosenbach, a typical Gram-positive bacterium, and Bacillus subtitles. After TiO₂ treatment, structure changes of cells were directly observed by TEM, and sterilization efficiency were detected with plate counting method. Compared with pure TiO₂ films, modified TiO₂ films show a higher bactericidal rate. Doping of Fe³⁺ improves the bactericidal rate of TiO₂ films on Escherichia coli from 87.4% to 95.8%, and on Staphyloccocus aureus Rosenbach from 79.4% to 88.3%, and on Bacillus subtitles from 80.4% to 86.3%, respectively. Similarly doping of Ce⁴⁺ also increases the bactericidal rate of pure TiO₂ film. Results suggest that bactericidal rate of pure TiO₂ film can be increased by doping of metal ions with acceptable concentration range. 2) It is the first report about a study on sterilization of TiO₂ on Halophilic archaeon. At first, sterilization efficiency of UV irradiation was detected on archaean. UV （365nm or 310nm） irradiation for 40 min were proved to be able to kill most of tested archaean. More than that, treatment by pure TiO₂ film under UV irradiation displays better sterilization efficiency. It seems that TiO₂ can been utilized effectively to sterilize archaean. Meanwhile, effects of metal ions doping also were detected on archaean. Compared with pure TiO₂ film, modified film shows higher sterilization efficiency. Such as, Fe³⁺ doping improve the sterilization efficiency from 88.6% to 94.5% under 365nm UV irradiation, and from 90.7% to 93.5 % under 310nm UV irradiation. Result of Ce⁴⁺ doping displays the same positive effects.3) The sterilization mechanism of TiO₂ film on Halophilic archaeon was firstly discussed in this paper. Under UV irradiation, TiO₂ is photo-excited and generates reactive oxygen species （ROS）, such as free radicals OH" and H₂O₂. Different from general bacteria, J7 Halophilic archaeon owns particular Na⁺-K⁺ balance system. Depend on this system, they maintain the normal range of intracellular Na⁺ concentration by excluding excessive Na⁺ ions rapidly, and survive the special environment with higher salt concentration. Upon treatment with TiO₂ photocatalyst, Na⁺ excluded by archaea might interfere with function of Ti bond, which will decrease the destruction potential of ROS on cell wall of J7 Halophilic archaeon. Meanwhile, with higher penetrability, H₂O₂ can enter archaea cells, degenerate proteins and fragmentize DNA molecules. It is obvious that, TiO₂ lead to death of J7 Halophilic archaeon mainly by destroying intracellular structures and increasing the leak of K⁺ ions.4) Up to now, reports about TiO₂ sterilization were confined to bacterium and eukaryotic domains. In this paper, except for detecting the sterilization efficiency of TiO₂ on archaeon, we further observe the ultrastructure change of archaeon treated by TiO₂ with TEM （Transmission Electron Microscope）, which definitely will supply a gap about utilization of TiO₂ in archaeon domain. At the same time, ultrastructural studies provide direct evidences for further exploring the bactericidal mechanism of TiO₂ photocatalyst. As a result, the evolutional relationships between archaeon and other life domains will be demonstrated comprehensively based on the new way of thinking provided by exploring death mechanism of archaeon.更多还原