【作者】 高晓明；

【导师】 李稳宏；

【作者基本信息】 西北大学 ， 化学工艺， 2013， 博士

【摘要】 目前,很多工业废水都具有有机物浓度高、难生物降解甚至有生物毒性等特点,尤其工业废水中的酚类物质对水体的危害最大,并且此危害具有持续性。因此,开发一种高效、实用、经济的含酚类物质废水处理技术迫在眉睫。光催化氧化有机污染物作为一个新兴的污染处理技术,是将化学氧化法进行强化与改进,与其它传统的水处理方法相比,具有工艺条件温和、处理成本低、氧化效果高、选择性好、反应速度快、可以将有机挥发酚氧化为无毒害的无机物、不产生二次污染等优点,受到人们的青睐。本文围绕光催化材料的设计合成及其光催化氧化处理含酚废水中的基本科学问题和技术问题,研究了Bi系列光催化材料的合成机理、结构特征以及光催化工艺过程,探索了Bi系列光催化材料在合成和应用过程中的一些基本理论、规律,可为含酚废水的光催化氧化处理技术提供一定的理论依据和借鉴。本论文主要研究成果：1、采用水热合成法制备了金属Cu掺杂改性的Bi2WO6光催化剂,使用XRD、XPS、DRS、SEM等表征手段对其进行了结构分析。结果表明,掺杂了金属Cu以后,样品的跃迁位置明显红移,并且对可见光的吸收强度高于Bi2W06。当金属Cu的掺杂量为0.5wt%时,Cu-Bi2WO6的特征衍射峰比较尖锐,其具有较高的结晶度。当前体液pH=0.6时,所制备的Cu-Bi2WO6的特征衍射峰最窄,峰强最大,样品为三维花球状结构,微孔尺寸大,比表面积为84.58m2/g。2、采用单因素讨论了各种因素对Cu-Bi2WO6光催化剂降解模拟含酚废水中的苯酚的影响,结果表明,在Cu-Bi2WO6催化剂(前体液pH为0.6,Cu掺杂量为0.5wt%)的用量为1.0mg/L,光源为300W金卤灯,空气流量为25mL/min时,Cu-Bi2WO6对模拟含酚废水中的苯酚降解效果最优。以Cu-Bi2WO6用量、空气流量、光照时间、光照强度为多因素考察对象,研究了多因素交互关系对苯酚的降解率的影响,结果表明所建立的回归模型是显著的,相关系数R2为0.9658。3、建立了基于兰缪尔和弗伦德利希的Cu-Bi2WO6表面吸附苯酚的模型方程式,分别为(?)和Qe=0.57298Ce0.66154,两种等温吸附模型能说明Cu-Bi2WO6对模拟含酚废水中的苯酚的吸附现象。建立了基于Langmuir-Hinshewood动力学模型的Cu-Bi2WO6光催化降解模拟含酚废水的动力学方程(?)+1.2306。4、采用水热合成法制备了金属Cu掺杂改性的BiVO4光催化剂,使用XRD、XPS、DRS、SEM等表征手段对其进行了结构分析。结果表明,在中性条件下所制备的Cu-BiVO4样品属于单斜晶系白钨矿,样品的特征衍射峰最窄,峰强最大,结晶度趋于成熟。当金属Cu的掺杂量为0.75wt%时,Cu-BiVO4样品的特征衍射峰比较尖锐,样品具有很高的结晶度。前体液pH=7时,合成的Cu-BiVO4样品为三维球状结构,表面形态复杂,比表面积为12.64m2/g。5、采用单因素讨论了各种因素对Cu-BiVO4光催化剂降解模拟含酚废水中的苯酚的影响,结果表明,在Cu-BiVO4催化剂(前体液pH为7,Cu掺杂量为0.75wt%)的用量为1.0mg/L,光源为300W氙灯,空气流量为30mL/min时,Cu-BiVO4对模拟含酚废水中的苯酚降解效果最优。以Cu-BiVO4用量、空气流量、光照时间、光照强度为多因素考察对象,研究了多因素交互关系对苯酚的降解率的影响,结果表明所建立的回归模型是显著的,相关系数R2为94.93%。6、建立了基于兰缪尔和弗伦德利希的Cu-BiVO4表面吸附苯酚的模型方程式,分别为(?)和Qe=0.760606Ce0.76684,两种等温吸附模型能说明Cu-BiVO4对模拟含酚废水中的苯酚的吸附现象。建立了基于Langmuir-Hinshewood动力学模型的Cu-BiVO4光催化降解模拟含酚废水的动力学方程(?)+2.1494。本论文所取得研究结果,不但为材料化学与环境科学提供了新的研究内容,而且为合成表面结构特殊且具有光催化性能的半导体金属复合材料提供了新的思路,同时也为半导体金属复合材料光催化综合治理工业含酚废水提供借鉴意义。更多还原

【Abstract】 At present, many industrial wastewaters have lots of characteristics, such as high concentration of organic substance, biodegradable and biological toxicity. Especially, the phenolic compound in industrial wastewater is most harmful, and the harm is persistent. Therefore, to explore an effective treatment technology of phenol-containing wastewater is imminent. As a new pollution treatment technology, photocatalytic oxidation is an enhanced and improved chemical oxidation method. Compared with other traditional water treatment method, the photocatalytic oxidation have a lots of advantages, such as, mild reaction conditions, low treatment cost, high oxidation effect, good selectivity, fast reaction speed, and organic volatile phenol can be oxidized to non-harmfully inorganic compounds. So, the photocatalytic oxidation has been widely studied.The study mainly centers on the basic science and technology issues in the synthesis and photocatalytic oxidation application of photocatalytic materials. The synthesis mechanism, structure characteristics and photocatalysis process of Bi-containing photocatalysts are reasearched. Lots of basic theory and rules of synthesis process and application process of Bi-containing photocatalysts are explored. The results hereby can provide the theoretical reference for phenol wastewater treatment by photocatalytic oxidation. The following several aspects of research are discussed in this paper:1. The Cu doping Bi2WO6photocatalysts are prepared by hydrothermal method and characterized by XRD、XPS、DRS and SEM. The results show that, after doped Cu, the Cu-Bi2WO6photocatalysts has a significant red-shift in the absorption band, and the absorption intensity increases greatly in the visible region. When the amount of Cu doping is0.5wt%, diffraction peaks of Cu-Bi2WO6are sharp and Cu-Bi2WO6has a higher crystallinity. While the pH value of preparation is0.6, the diffraction peaks are most narrow and the peak intension is larger. The morphology and microstructure of Cu-Bi2WO6is3D flower spherical structure, the size of micro-porosity is large, and specific surface area is84.58m2/g.2. The various factors of photocatalytic degradation of phenol-containing wastewater over Cu-Bi2WO6photocatalysts are discussed by single factor experiment. The results show that the optimal degradation effect of phenol-containing wastewater could reach at a Cu-Bi2WO6catalyst (pH value of preparation is0.6, Cu doping is0.5wt%) dosage of1.0mg/L, and an air flow rate of25mL/min upon being illuminated with300W metal halide lamp. Cu-Bi2WO6dosage, air flow, light, light intensity as a multiple factor, the degradation effect is investigated by interaction of multiple factors, the results show that the establishment of the regression model was significant, orrelation coefficient R2is0.9658.3. The model equations of adsorption of phenol over Cu-Bi2WO6, Qe=0.31437Ce/1+0.02286Ce and Qe=0.57298Ce0.66154, are established. Both types of isothermal adsorption model can descript the adsorption phenomena of phenol over Cu-Bi2WO6.Based on Langmuir-Hinshewood model, the kinetics equation of photocatalytic degradation of phenol-containing wastewater is established. The correlation coefficient R2is0.9919, and kinetic parameters of Langmuir-Hinshewood model are k=0.8126, KL-H=0.02354. The Cu doping BiVO4photocatalysts are prepared by hydrothermal method and characterized by XRD、XPS、DRS and SEM. The results show that, the Cu-BiVO4preparated at neutral conditions belongs to the monoclinic crystal system scheelite, the diffraction peaks are most narrow, the peak intension is larger. When the amount of Cu doping is0.75wt%, diffraction peaks of Cu-BiVO4are sharp and Cu-BiVO4has a higher crystallinity. While the pH value of preparation is7, the morphology and microstructure of Cu-BiVO4is3D spherical structure and has a complicated surface morphology, the size of micro-porosity is large, and specific surface area is12.64m2/g.5. The various factors of photocatalytic degradation of phenol-containing wastewater over Cu-BiVO4photocatalysts are discussed by single factor experiment. The results show that the optimal degradation effect of phenol-containing wastewater could reach at a Cu-BiVO4catalyst (pH value of preparation is7, Cu doping is0.75wt%) dosage of1.0mg/L, and an air flow rate of30mL/min upon being illuminated with300W xenon lamp. Cu-BiVO4dosage, air flow, light, light intensity as a multiple factor, the degradation effect is investigated by interaction of multiple factors, the results show that the establishment of the regression model was significant, orrelation coefficient R2is94.93%. 6. The model equations of adsorption of phenol over Cu-BiVO4, Qe=0.83986Ce/1+0.01254Ce and Qe=0.760606Ce0.76684,are established. Both types of isothermal adsorption model can descript the adsorption phenomena of phenol over Cu-BiVO4Based on Langmuir-Hinshewood model, the kinetics equation of photocatalytic degradation of phenol-containing wastewater is established. The correlation coefficient R2is0.9961, and kinetic parameters of Langmuir-Hinshewood model are k=0.4652, KL-H=0.0695The obtained outcome of this study, not only enriches the contents of materials chemistry and environmental science, but also provides a new idea to prepare metal composite oxides materials with diverse surface structure and photocatalytic properties, and also provides a consulting effect to photocatalytic treatment of industrial wastewaters with metal composite oxides materials.更多还原