负载型纳米TiO_2催化剂的制备及其在难降解有机废水处理中的应用研究
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摘要
本文从研制和改进催化剂材料入手，制备新型负载型纳米TiO_2催化剂，并在其结构表征和吸附性能考察的基础上，对对氯苯酚的降解开展了系统的研究。并通过对催化剂的改性来考察其对甲基橙染料废水降解效率的提高。
采用常压金属有机物化学气相沉积(Metal Organic Chemical Vapor Deposition)技术在活性炭表面沉积构成纳米TiO_2催化剂。对该负载型纳米TiO_2催化剂进行表征，XRD图谱表明煅烧温度为773K时负载的TiO_2晶型结构为锐钛矿，873K时出现金红石相。TEM分析表明负载量为8％(wt)时负载的TiO_2颗粒的粒径为10～20nm；载体负载前后BET面积改变仅为6％，表明负载TiO_2后对活性炭结构影响不大。在光催化反应体系下，加入负载型TiO_2后降解对氯苯酚(4-cp)，实验结果表明负载型TiO_2具有较高的光催化效率。
由于TiO_2半导体的禁带宽度较大，且量子效率相对较低，对某些有机污染物(如甲基橙)光催化活性不明显。为改善负载型纳米TiO_2催化剂的性能，对采用MOCVD技术制备出的TiO_2／沸石催化剂，通过硝酸银溶液浸渍—紫外光照还原沉积的方法将银沉积在TiO_2表面，获得载银的改性TiO_2／沸石催化剂。通过对甲基橙光照降解的实验表明，光催化性能较改性前可提高1倍。最佳硝酸银浸渍液浓度为10~(-3)M，此时该催化剂的光催化性能接近纳米TiO_2粉末(Degussa P25)，但进一步提高硝酸银浸渍液浓度，催化剂光催化性能又降低。实验通过XRD和TEM对载银TiO_2／沸石催化剂的表征，进一步分析了其催化机理。
对该催化剂对对氯苯酚(4-cp)的吸附行为进行了分析，发现催化剂对4-cp的吸附较好的符合Langmuir吸附等温方程，4-cp在催化剂上以表面单分子形式吸附。在紫外光照情况下对4-cp进行催化降解实验，并利用Langmuir-Hinshelwood动力学模型探讨了TiO_2／活性炭催化剂对4-cp的吸附行为和光催化降解之间的关系，求出4-cp降解反应速率常数K_r。实验结果显示暗吸附和光照吸附条件下的吸附常数K_b存在差异，发现在紫外光照条件下催化剂对4-cp的吸附明显增强，对4-cp的吸附不再完全是表面单分子吸附形式。
In this work, a new type of nanometer TiO2/AC catalyst was prepared. The structure characteristics and adsorption behavior of this novel catalyst were investigated. The photodegradation of p-chlorophenol by using this catalyst was studied. The silver-modified TiO2/zeolite catalyst was also prepared in order to improve the photodegradation efficiency of methyl orange waste water.
The atmospheric pressure metal-organic chemical vapor deposition (MOCVD) technology was used to load TiO2 onto the surface of active carbon. XRD results showed that TiO2 calcined at 773K is in anatase phase and rutile phase at 873K. The results of TEM suggested that TiO2 particles were in the range 10 to 20 nm when the amount of titania supported was 8%(wt). BET surface area was only reduced by 6% with the loading amount was 8%(wt), so it can be concluded that the framework of active carbon was not destructured strongly. The degradation of 4-CP was enhanced with the samples of TiO2-AC added to the photocatalytic system.
To some organic contaminations such as methyl orange, the photodegradation performance of supported TiO2 catalyst is not satisfied. Catalysts of silver-modified TiO2/zeolite containing different amounts of Ag via a two-step dipping of AgNO3 solution and UV-irradiation process were examined for their improved catalytic activity towards photodegradation of methyl orange. The silver modified TiO2/zeolite catalysts present enhanced photocatalytic efficiency one time more than non-silver modified TiO2/zeolite catalysts did. The optimum silver nitrate concentration of the dipping solution was found to be 10-3M, whose photodegradation efficiency is approximate to that of titanium dioxide powder (Degussa P25). While with the Ag+-ion concentration further increased in dipping solution, the photocatalyst efficiency of the silver-modified catalysts decreased. The silver-modified catalysts were characterized with XRD and TEM. In addition, the presence of metallic silver always produces an increase in activity in compari
son with Ag+ ions. This can be explained by the increase in the electron-hole pair separation efficiency induced by
trapping of electrons by metallic silver.
The adsorption characteristics of 4-cp on TiO2/AC catalyst system have been investigated. The result shows that The adsorption isotherm forms of 4-cp adsorbed on TiO2/AC catalyst follows Langmuir adsorption model. The relationship of the photodegradation of 4-cp and the adsorption behavior of 4-cp on TiCVAC catalyst can be described by the Langmuir-Hinshelwood kinetics model, we can conclude the reaction rate of the photodegradation of 4-cp by this model. The adsorption equlibrium constant calculated by Langmuir adsorption isotherms under dark adsorption conditions is smaller than calculated by L-H kinetics model under UV-light photodegradation, which shows that the adsorption of 4-cp on TiO2/AC catalyst has increased when under UV-light photodegradation.
采用常压金属有机物化学气相沉积(Metal Organic Chemical Vapor Deposition)技术在活性炭表面沉积构成纳米TiO_2催化剂。对该负载型纳米TiO_2催化剂进行表征，XRD图谱表明煅烧温度为773K时负载的TiO_2晶型结构为锐钛矿，873K时出现金红石相。TEM分析表明负载量为8％(wt)时负载的TiO_2颗粒的粒径为10～20nm；载体负载前后BET面积改变仅为6％，表明负载TiO_2后对活性炭结构影响不大。在光催化反应体系下，加入负载型TiO_2后降解对氯苯酚(4-cp)，实验结果表明负载型TiO_2具有较高的光催化效率。
由于TiO_2半导体的禁带宽度较大，且量子效率相对较低，对某些有机污染物(如甲基橙)光催化活性不明显。为改善负载型纳米TiO_2催化剂的性能，对采用MOCVD技术制备出的TiO_2／沸石催化剂，通过硝酸银溶液浸渍—紫外光照还原沉积的方法将银沉积在TiO_2表面，获得载银的改性TiO_2／沸石催化剂。通过对甲基橙光照降解的实验表明，光催化性能较改性前可提高1倍。最佳硝酸银浸渍液浓度为10~(-3)M，此时该催化剂的光催化性能接近纳米TiO_2粉末(Degussa P25)，但进一步提高硝酸银浸渍液浓度，催化剂光催化性能又降低。实验通过XRD和TEM对载银TiO_2／沸石催化剂的表征，进一步分析了其催化机理。
对该催化剂对对氯苯酚(4-cp)的吸附行为进行了分析，发现催化剂对4-cp的吸附较好的符合Langmuir吸附等温方程，4-cp在催化剂上以表面单分子形式吸附。在紫外光照情况下对4-cp进行催化降解实验，并利用Langmuir-Hinshelwood动力学模型探讨了TiO_2／活性炭催化剂对4-cp的吸附行为和光催化降解之间的关系，求出4-cp降解反应速率常数K_r。实验结果显示暗吸附和光照吸附条件下的吸附常数K_b存在差异，发现在紫外光照条件下催化剂对4-cp的吸附明显增强，对4-cp的吸附不再完全是表面单分子吸附形式。
In this work, a new type of nanometer TiO2/AC catalyst was prepared. The structure characteristics and adsorption behavior of this novel catalyst were investigated. The photodegradation of p-chlorophenol by using this catalyst was studied. The silver-modified TiO2/zeolite catalyst was also prepared in order to improve the photodegradation efficiency of methyl orange waste water.
The atmospheric pressure metal-organic chemical vapor deposition (MOCVD) technology was used to load TiO2 onto the surface of active carbon. XRD results showed that TiO2 calcined at 773K is in anatase phase and rutile phase at 873K. The results of TEM suggested that TiO2 particles were in the range 10 to 20 nm when the amount of titania supported was 8%(wt). BET surface area was only reduced by 6% with the loading amount was 8%(wt), so it can be concluded that the framework of active carbon was not destructured strongly. The degradation of 4-CP was enhanced with the samples of TiO2-AC added to the photocatalytic system.
To some organic contaminations such as methyl orange, the photodegradation performance of supported TiO2 catalyst is not satisfied. Catalysts of silver-modified TiO2/zeolite containing different amounts of Ag via a two-step dipping of AgNO3 solution and UV-irradiation process were examined for their improved catalytic activity towards photodegradation of methyl orange. The silver modified TiO2/zeolite catalysts present enhanced photocatalytic efficiency one time more than non-silver modified TiO2/zeolite catalysts did. The optimum silver nitrate concentration of the dipping solution was found to be 10-3M, whose photodegradation efficiency is approximate to that of titanium dioxide powder (Degussa P25). While with the Ag+-ion concentration further increased in dipping solution, the photocatalyst efficiency of the silver-modified catalysts decreased. The silver-modified catalysts were characterized with XRD and TEM. In addition, the presence of metallic silver always produces an increase in activity in compari
son with Ag+ ions. This can be explained by the increase in the electron-hole pair separation efficiency induced by
trapping of electrons by metallic silver.
The adsorption characteristics of 4-cp on TiO2/AC catalyst system have been investigated. The result shows that The adsorption isotherm forms of 4-cp adsorbed on TiO2/AC catalyst follows Langmuir adsorption model. The relationship of the photodegradation of 4-cp and the adsorption behavior of 4-cp on TiCVAC catalyst can be described by the Langmuir-Hinshelwood kinetics model, we can conclude the reaction rate of the photodegradation of 4-cp by this model. The adsorption equlibrium constant calculated by Langmuir adsorption isotherms under dark adsorption conditions is smaller than calculated by L-H kinetics model under UV-light photodegradation, which shows that the adsorption of 4-cp on TiO2/AC catalyst has increased when under UV-light photodegradation.
引文
1．胡春，王怡中等，多相光催化氧化的理论与实践发展，[J]．环境科学进展，1995，3(1)：5～8．
2．雷乐成，汪大翚。水处理高级氧化技术，化学工业出版社，北京，2001．
3. Michael R. Hoffmann, Scot T. Martin, Wonyong Choi, Detlef W.,Bahnemannt. Environmental applications of semiconductor photocatalysis. [J]. Chem. Rev, 1995, 95, 69-96.
4. Braun A. M., Maurette M. T., Oliveros .. E., Photochemical Technology, Wiley &
Sons: New York, Chichester, 1991.
5．刘勇弟，徐寿昌，几种类Fenton试剂的氧化特性及在工业废水处理中的应用，[J]．上海环境科学，1994，13(3)．
6. Fujishima A., Rao T. N., Tryk D. A., Titanium dioxide photocatalysis. [J]. Photochem. Photobiol. C: Photochem. Rev., 2000, 1 : 1-21.
7. Mills A., Lehuntes S., An overview of semiconductor photocatalysis, [J]. Photochem. Photobiol. A: Chem., 1997, 108:1.
8. Fank S. N., Bard A. J., Heterogeneous photocatalytic oxidation of cyanide and sulfite in aqueous solutions at semiconductor powders. [J]. Phys. Chem., 1977,81:1484-1488.
9. Carey J. H., Lawrence J., Bull., Environ. Contam. Toxicol., 1976,16:697.
10. Fox M. A., Dulay M., T., Heterogeneous photocatalysis. [J]. Chem. Rev., 1993,93:341-357.
11. Robert D., Malato S., Development of the Permeability/Performance Reference Compound Approach for In Situ Calibration of Semipermeable Membrane Devices. [J]. Environ Sci Technol., 2002,291:85-89.
12. Roland G., Detoxification and recycling of wastewater by solar-catalytic treatment. [J]. Wat. Sci. Tech., 1997,35(4): 149-156.
13. Minero C., Pelizzetti E., Malato S., Blanco J., Large solar plant photocatalytic water decontamination: Effect of operational parameters. [J]. Solar Energy, 1996,56(5): 421-428。
14. Hoffmann M. R., Martin S. T., Choi W., Environmental Applications of Semiconductor Photocatalysis. [J]. Chem. Rev., 1995,95:69-96.
15. Elmosi T. M., Budakowski W. R., Photocatalytic Degradation of 1,10-Dichlorodecane in Aqueous Suspensions of TiO_2: A Reaction of Adsorbed Chlorinated Alkane with Surface Hydroxyl Radicals. [J]. Environ Sci Technol., 2000,34: 1018-1022.
16. Joseph R., Koichi Y., Kiminori U., Fundamental Reactions in Illuminated Titanium Dioxide Nanocrystallite Layers Studied by Pulsed Laser. [J]. Phys. Chem. B, 1998,102:11689-1695.
17. Sun L., Bolton J. R., Determination of the Quantum Yield for the Photochemical Generation of Hydroxyl Radicals in TiO_2 Suspensions. [J]. Phys. Chem., 1996,100: 4127-4134.
18. Schwarz P. F., Turro N., J., A New Method To Determine the Generation of Hydroxyl Radicals in Illuminated TiO_2 Suspensions. [J]. Phys. Chem. B, 1997,101:7127-7134.
19. Mao Y., Schoneich C., Identification of organic acids and other intermediates in oxidative degradation of chlorinated ethanes on titania surfaces en route to mineralization: a combined photocatalytic and radiation chemical study. [J]. Phys. Chem., 1991,95:10080-10089.
20. Sun Y., Evidence for a surface dual hole-radical mechanism in the titanium dioxide photocatalytic oxidation of 2,4-D. [J]. Environ Sci Technol., 1995,25:2065-2072.
21. Assabane A., Yahia A., Photocatalytic degradation of polycarboxylic benzoic acids in UV-irradiated aqueous suspensions of titania.: Identification of intermediates and reaction pathway of the photomineralization of trimellitic acid. [J]. Appl. Catal. B: Environ., 2000,24:71-87.
22. Wang Y., Hong C-S., TiO_2-mediated photomineralization of 2-chlorobiphenyl: the role of O_2, [J]. Water Research, 34,10:2791-2797.
23. Dionysiou D. D., Suidan M. T., Effect of ionic strength and hydrogen peroxide on the photocatalytic degradation of 4-chlorobenzoic acid in water, [J]. Appl. Catal. B: Environ., 2000,26:153-171.
24. Zhang Z., Wang C. C., Zakaria R., Role of Particle Size in Nanocrystalline TiO_2-Based Photocatalysts. [J]. Phys.Chem.B, 1998,102:10871--10878.
25. Serpone N., Law less D., Subnanosecond Relaxation Dynamics in TiO_2 Colloidal Sols (Particle Sizes Rp= 1.0-13.4 nm). Relevance to Heterogeneous Photocatalysis. [J]. Phys.Chem. 1995,99:16655-16661.
26. Furube A., Asahi T., Charge Carrier Dynamics of Standard TiO_2 Catalysts Revealed by Femtosecond Diffuse Reflectance Spectroscopy [J]. Phys.Chem.B, 1999,103:3120--3127.
27. Wang chuanyi, Liu Chunyan, Shen Tao, Chemical Journal of Chinese Universities, (高等学校化学学报), 1999,20(11): 1787—1789.
28. Fu X., Zeltner W. A., Anderson M. A., The gas-phase photocatalytic mineralization of benzene on porous titania-based catalysts. [J]. Appl. Catal. B: Environ., 1995,6:209.
29. Harade K., Hisanaga T., Photocatalytic degradation of organophosphorous insecticides in aqueous semiconductor suspensions. [J]. Water Research, 1990,24:1415-1417.
30. Choi W.Y., Terrmin A., Hoffmann M.R., The Role of Metal Ion Dopants in Quantum-Sized TiO_2: Correlation between Photoreactivity and Charge Cartier Recombination Dynamics. [J]. Phys. Chem., 1994,98:13669-13679.
31. Hiroyuki Uchida, Shigeyoshi Itoh, Hiroshi Yoneyama. Photocatalytic decomposition of propyzamide using TiO_2 supported on active carbon [J]. Chem Lett, 1993,1995-1998.
32. Tsukasa Torimoto, Shigeyoshi Ito, Susumu Kuwabata, Hiroshi Yoneyama. Effects of adsorbents used as supports for titanium dioxide loading on on photocatalytic degradation of propyzamide [J]. Environ Sci Technol, 1996, 30:1275-1281.
33. Moene R.,.Makkee M, Moulijn J.A. Chemical vapour depostion as a novel technique for catalyst preparation ;modelling of active phase profiles [J].The Chemical Engineering Journal, 1993, 53:13-24.
34. Dossi C, Schaefer J, Sachtler, W M H. Mechanism of particle formation in decoposition Re_2(CO)_(10) on NaY and NaHYzeolites:effect of prereduced Pt clusters in the supercages [J]. J Mol. Catal., 1989, 52: 193-209.
35. Ding, Zhe Hu, XijunYue, Po L, Lu, Gao Q.Greenfield, Paul F. Synthesis of anatase TiO_2 supported on porous solids by chemical vapor deposition. [J]. Catalysis Today, 2001, 68 : 173-182.
36. Vamathevan V., Amal R., Photocatalytic oxidation of organics in water using pure and silver-modified titanium dioxide particles. [J]. Photochem. Photobiol. A: Chem., 2002,148:233-245.
37. Sclafani A., Hermann J. M., Influence of metallic silver and of platinum-silver
bimetallic deposits on the photocatalytic activity of titania (anatase and rutile) in organic and aqueous media. [J]. Photochem. Photobiol. A: Chem., 1998,113:181-188.
38. Wu G. W., Chan K. Y., Morphology of platinum clusters on graphite at different loadings. [J]. Surf. Sci., 1996,365:38-52.
39．唐玉朝，胡春，TiO_2光催化反应机理及动力学研究进展．化学进展．2002 Vol．14，No．3．
40. Shuzo K., Mitsuhiro J., Koji T., Takashi I., Photocatalytic Degradation of Some Methyl Perfluoroalkyl Ethers on TiO_2 Particles in Air: The Dependence on the Dark-Adsorption, the Products, and the Implication for a Possible Tropospheric Sink. [J]. Environ. Sci. TechnoL, 1999,33:1071-1076.
2．雷乐成，汪大翚。水处理高级氧化技术，化学工业出版社，北京，2001．
3. Michael R. Hoffmann, Scot T. Martin, Wonyong Choi, Detlef W.,Bahnemannt. Environmental applications of semiconductor photocatalysis. [J]. Chem. Rev, 1995, 95, 69-96.
4. Braun A. M., Maurette M. T., Oliveros .. E., Photochemical Technology, Wiley &
Sons: New York, Chichester, 1991.
5．刘勇弟，徐寿昌，几种类Fenton试剂的氧化特性及在工业废水处理中的应用，[J]．上海环境科学，1994，13(3)．
6. Fujishima A., Rao T. N., Tryk D. A., Titanium dioxide photocatalysis. [J]. Photochem. Photobiol. C: Photochem. Rev., 2000, 1 : 1-21.
7. Mills A., Lehuntes S., An overview of semiconductor photocatalysis, [J]. Photochem. Photobiol. A: Chem., 1997, 108:1.
8. Fank S. N., Bard A. J., Heterogeneous photocatalytic oxidation of cyanide and sulfite in aqueous solutions at semiconductor powders. [J]. Phys. Chem., 1977,81:1484-1488.
9. Carey J. H., Lawrence J., Bull., Environ. Contam. Toxicol., 1976,16:697.
10. Fox M. A., Dulay M., T., Heterogeneous photocatalysis. [J]. Chem. Rev., 1993,93:341-357.
11. Robert D., Malato S., Development of the Permeability/Performance Reference Compound Approach for In Situ Calibration of Semipermeable Membrane Devices. [J]. Environ Sci Technol., 2002,291:85-89.
12. Roland G., Detoxification and recycling of wastewater by solar-catalytic treatment. [J]. Wat. Sci. Tech., 1997,35(4): 149-156.
13. Minero C., Pelizzetti E., Malato S., Blanco J., Large solar plant photocatalytic water decontamination: Effect of operational parameters. [J]. Solar Energy, 1996,56(5): 421-428。
14. Hoffmann M. R., Martin S. T., Choi W., Environmental Applications of Semiconductor Photocatalysis. [J]. Chem. Rev., 1995,95:69-96.
15. Elmosi T. M., Budakowski W. R., Photocatalytic Degradation of 1,10-Dichlorodecane in Aqueous Suspensions of TiO_2: A Reaction of Adsorbed Chlorinated Alkane with Surface Hydroxyl Radicals. [J]. Environ Sci Technol., 2000,34: 1018-1022.
16. Joseph R., Koichi Y., Kiminori U., Fundamental Reactions in Illuminated Titanium Dioxide Nanocrystallite Layers Studied by Pulsed Laser. [J]. Phys. Chem. B, 1998,102:11689-1695.
17. Sun L., Bolton J. R., Determination of the Quantum Yield for the Photochemical Generation of Hydroxyl Radicals in TiO_2 Suspensions. [J]. Phys. Chem., 1996,100: 4127-4134.
18. Schwarz P. F., Turro N., J., A New Method To Determine the Generation of Hydroxyl Radicals in Illuminated TiO_2 Suspensions. [J]. Phys. Chem. B, 1997,101:7127-7134.
19. Mao Y., Schoneich C., Identification of organic acids and other intermediates in oxidative degradation of chlorinated ethanes on titania surfaces en route to mineralization: a combined photocatalytic and radiation chemical study. [J]. Phys. Chem., 1991,95:10080-10089.
20. Sun Y., Evidence for a surface dual hole-radical mechanism in the titanium dioxide photocatalytic oxidation of 2,4-D. [J]. Environ Sci Technol., 1995,25:2065-2072.
21. Assabane A., Yahia A., Photocatalytic degradation of polycarboxylic benzoic acids in UV-irradiated aqueous suspensions of titania.: Identification of intermediates and reaction pathway of the photomineralization of trimellitic acid. [J]. Appl. Catal. B: Environ., 2000,24:71-87.
22. Wang Y., Hong C-S., TiO_2-mediated photomineralization of 2-chlorobiphenyl: the role of O_2, [J]. Water Research, 34,10:2791-2797.
23. Dionysiou D. D., Suidan M. T., Effect of ionic strength and hydrogen peroxide on the photocatalytic degradation of 4-chlorobenzoic acid in water, [J]. Appl. Catal. B: Environ., 2000,26:153-171.
24. Zhang Z., Wang C. C., Zakaria R., Role of Particle Size in Nanocrystalline TiO_2-Based Photocatalysts. [J]. Phys.Chem.B, 1998,102:10871--10878.
25. Serpone N., Law less D., Subnanosecond Relaxation Dynamics in TiO_2 Colloidal Sols (Particle Sizes Rp= 1.0-13.4 nm). Relevance to Heterogeneous Photocatalysis. [J]. Phys.Chem. 1995,99:16655-16661.
26. Furube A., Asahi T., Charge Carrier Dynamics of Standard TiO_2 Catalysts Revealed by Femtosecond Diffuse Reflectance Spectroscopy [J]. Phys.Chem.B, 1999,103:3120--3127.
27. Wang chuanyi, Liu Chunyan, Shen Tao, Chemical Journal of Chinese Universities, (高等学校化学学报), 1999,20(11): 1787—1789.
28. Fu X., Zeltner W. A., Anderson M. A., The gas-phase photocatalytic mineralization of benzene on porous titania-based catalysts. [J]. Appl. Catal. B: Environ., 1995,6:209.
29. Harade K., Hisanaga T., Photocatalytic degradation of organophosphorous insecticides in aqueous semiconductor suspensions. [J]. Water Research, 1990,24:1415-1417.
30. Choi W.Y., Terrmin A., Hoffmann M.R., The Role of Metal Ion Dopants in Quantum-Sized TiO_2: Correlation between Photoreactivity and Charge Cartier Recombination Dynamics. [J]. Phys. Chem., 1994,98:13669-13679.
31. Hiroyuki Uchida, Shigeyoshi Itoh, Hiroshi Yoneyama. Photocatalytic decomposition of propyzamide using TiO_2 supported on active carbon [J]. Chem Lett, 1993,1995-1998.
32. Tsukasa Torimoto, Shigeyoshi Ito, Susumu Kuwabata, Hiroshi Yoneyama. Effects of adsorbents used as supports for titanium dioxide loading on on photocatalytic degradation of propyzamide [J]. Environ Sci Technol, 1996, 30:1275-1281.
33. Moene R.,.Makkee M, Moulijn J.A. Chemical vapour depostion as a novel technique for catalyst preparation ;modelling of active phase profiles [J].The Chemical Engineering Journal, 1993, 53:13-24.
34. Dossi C, Schaefer J, Sachtler, W M H. Mechanism of particle formation in decoposition Re_2(CO)_(10) on NaY and NaHYzeolites:effect of prereduced Pt clusters in the supercages [J]. J Mol. Catal., 1989, 52: 193-209.
35. Ding, Zhe Hu, XijunYue, Po L, Lu, Gao Q.Greenfield, Paul F. Synthesis of anatase TiO_2 supported on porous solids by chemical vapor deposition. [J]. Catalysis Today, 2001, 68 : 173-182.
36. Vamathevan V., Amal R., Photocatalytic oxidation of organics in water using pure and silver-modified titanium dioxide particles. [J]. Photochem. Photobiol. A: Chem., 2002,148:233-245.
37. Sclafani A., Hermann J. M., Influence of metallic silver and of platinum-silver
bimetallic deposits on the photocatalytic activity of titania (anatase and rutile) in organic and aqueous media. [J]. Photochem. Photobiol. A: Chem., 1998,113:181-188.
38. Wu G. W., Chan K. Y., Morphology of platinum clusters on graphite at different loadings. [J]. Surf. Sci., 1996,365:38-52.
39．唐玉朝，胡春，TiO_2光催化反应机理及动力学研究进展．化学进展．2002 Vol．14，No．3．
40. Shuzo K., Mitsuhiro J., Koji T., Takashi I., Photocatalytic Degradation of Some Methyl Perfluoroalkyl Ethers on TiO_2 Particles in Air: The Dependence on the Dark-Adsorption, the Products, and the Implication for a Possible Tropospheric Sink. [J]. Environ. Sci. TechnoL, 1999,33:1071-1076.