None

Crystalline TiO2 nanoparticles were synthesized by hydrolysis of titanium (IV) isopropoxide (TTIP) in the Aerosol OT (AOT)－cyclohexane microemulsion at controlled temperature. The influence of various reaction conditions, such as mixing energy ( ), [AOT] concentration (W), [TTIP] concentration (R), temperature (T), and aging (t) on the particle size were investigated. The nano-TiO2 particles were characterized for specific surface area (Brunauer-Emmett-Teller, BET) in addition to X-ray diffraction (XRD) and X-ray spectroscopy (XPS) as to determine the particle size, crystalline state, chemical composition, surface charge, and binding energy. The photocatalytic activity was assessed using methylene blue as probe.
Results showed that the particle size was in the range from 13.7 to 31.4 nm based on BET measurements. The size of the particle grows with mixing energy until log ( ) = 2.02; further increase in mixing rate caused particle breakup. In micelle solution, the particle size decreased with increase in W. In true solution the particle size increased with W. However, increase in R increased the particle size which reached a maximum value at a critical value of log R = -0.26, then decreased upon further increase in R. The activation energy (Ea) was calculated using Arrenhius plot and a value of -5.96 and -2.17 kJ mol-1 was obtained. Results of particle size analysis from XRD and BET were consistent with each other. Crystalline pattern was proved to be anatase. Furthermore, the photocatalytic activity appeared to optimum with particle size between 22.0-25.1 nm and best crystalline pattern.
Titanium dioxide (TiO2) synthesized using the thermal hydrolysis method in our laboratory was used as the photocatalyst in this study to degrade low concentration phenol in aqueous solution. A 150 mL batch reactor was used to carry out the degradation of 0.385 mM phenol solution (pH = 6.5) in room temperature (25 oC) with 0.5 g L-1 TiO2 and irradiated with 10.8 mW cm-2 light intensity for 8 hours. Major intermediate products include hydroquinone (HQ) with the highest quantity followed by catechol (CA), p-benzoquinone (BQ), resorcinol (RES); tri-hydroquinone (THQ) is the secondary intermediate. The by-products consist of 6 organic acids including the six-carbon trans, trans-muconic acid (t,t-MA), the four-carbon maleic acid (MA), the three-carbon propionic acid (PA), the two-carbon oxalic acid (OA) and acetic acid (AA) as well as the one-carbon formic acid (FA). Among these acids, oxalic acid is the most abundant followed by formic acid; the six-carbon t,t-MA is one of the by-products with a lagged formation period. The pathway of intermediate product formation was mathematically calculated and simulated using first-order reaction kinetics models. The reaction rate constants were statistically calculated using functions provided in Microsoft Excel 2003; the simulated results show that the predicted and measured concentrations of the reactant and products in samples collected at various times are consistent.

TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS I
ABSTRACT II
TABLE OF CONTENTS IV
LIST OF TABLES VII
LIST OF FIGURES VIII

Chapter 1 INTRODUCTION 1
1.1 Preparation of crystalline nanosize titania by microemulsion 1
1.2 Intermediates and kinetic modeling on photocatalytic degradation of phenol 3

Chapter 2 LITERATURE REVIEW 6
2.1 Characteristics of TiO2 6
2.2 Preparation of TiO2 7
2.2.1 Thermal hydrolysis technique 7
2.2.2 Hydrothermal processing 8
2.2.3 Sol-gel method 9
2.2.4 Microemulsion technique 10
2.3 Fundamentals of photocatalysis 11
2.4 Degradation mechanisms 13
2.4.1 Langmuir-Hinshelwood mechanism 13
2.4.2 Delplot technique 15
2.5 Decolorization of dyes 15
2.6 Decomposition of phenol 16
2.7 Application of solar energy in the photocatalysis 16
2.8 Toxicity of intermediates 18
2.9 Particle size effect 19

Chapter 3 MATERIALS AND METHODS 23
3.1 Preparation of crystalline nanosize titania by microemulsion 23
3.1.1 Reagents and materials 23
3.1.2 Synthesis 23
3.1.3 Physical characterization 24
3.1.4 Photocatalytic experiments 25
3.2 Intermediates and Kinetic modeling on photocatalytic degradation of phenol 26
3.2.1 Reagents 26
3.2.2 Laboratory synthesis of titanium oxide powder 27
3.2.3 Analyzing physical characteristic of the synthesized titanium dioxide 27
3.2.4 Photocatalytic reaction 29
3.2.5 Analysis of reactant 29
3.2.6 Calibration of the kinetic model 30

Chapter 4 RESULTS AND DISCUSSION 33
4.1 Preparation of crystalline nanosize titania by microemulsion 33
4.1.1 Characterization of XRD and XPS 33
4.1.2 Effect of mixing energy 34
4.1.3 Effect of W 35
4.1.4 Effect of R 35
4.1.5 Effect of temperature 36
4.1.6 Effect of aging 37
4.1.7 Photocatalytic activity 37
4.2 Intermediates and kinetic modeling on photocatalytic degradation of phenol 48
4.2.1 Physical characteristics of the synthesized titanium dioxide 48
4.2.2 Photocatalytic activity of synthesized titanium dioxide 50
4.2.3 Identification of products 51
4.2.4 Investigation of the reaction mechanism 53
4.2.5 Reaction kinetics and reaction rate constants 55

Chapter 5 CONCLUSIONS 69
5.1 Preparation of crystalline nanosize titania by microemulsion 69
5.2 Intermediates and kinetic modeling on photocatalytic degradation of phenol 70
5.3 Recommendations 71

REFERENCES 73
Curriculum Vitae 87

LIST OF TABLES
Page
Table 4.1 Summary of experimental conditions and prepared nanosize titania 39
Table 4.2 Degradation of phenol and production of intermediates with initial phenol concentration = 0.385 mM, Vo = 150 mL, [Synthesized-TiO2] = 0.5 g L-1, pH = 6.5, Temperature = 25 oC, Io = 10.8 mW cm-2 at 254 nm @ 2 cm 59
Table 4.3 Concentrations of organic acids at various reaction times with initial phenol concentration = 0.385 mM, Vo = 150 mL, [Synthesized-TiO2] = 0.5 g L-1, pH = 6.5, Temperature = 25 oC, Io = 10.8 mW cm-2 at 254 nm @ 2 cm 60
Table 4.4 The calculated pseudo-first-order rate constants for reaction network in Figure 4.13 61


LIST OF FIGURES
Page
Figure 2.1 Schematically illustrated mechanism of photocatalysis 22
Figure 3.1 Schematic plot of photocatalytic reactor 32
Figure 4.1 X-ray diffraction patterns 40
Figure 4.2 X-ray photoelectron spectroscopy (XPS) patterns of 25.1 nm 41
Figure 4.3 Relation between mixing energy and particle size 42
Figure 4.4 Relation between AOT concentration (W) and particle size 43
Figure 4.5 Relation between TTIP concentration (R) and particle size 44
Figure 4.6 Arrhenius plot of log (d) particle size versus 103(1/T) 45
Figure 4.7 Relation between aging (days) and particle size 46
Figure 4.8 Relation between photocatalytic degradation rate (R) and particle size 47
Figure 4.9 XRD pattern of synthesized-TiO2 62
Figure 4.10 SEM photograph of synthesized-TiO2 63
Figure 4.11 Comparison of phenol conversion under various experimental conditions at different irradiation times for the degrading phenol in aqueous solution (Experimental conditions: Vo = 150 mL, [Phenol]o = 0.5 mM, [Synthesized-TiO2] = 0.5 g L-1, pH = 3, Temperature = 25 oC, Io = 10 mW cm-2 at 365 nm @ 2 cm; 50 mW cm-2 at 254 nm @ 2 cm.) 64
Figure 4.12 Selectivity (molar ratio of product produced to phenol reacted) of various products vs. phenol conversion 65
Figure 4.13 Selectivity (molar ratio of acid produced to phenol converted) of organic acids produced vs. phenol conversion 66
Figure 4.14 Proposed main reaction pathway network for phenol oxidation in UV/TiO2 system 67
Figure 4.15 Comparison of calculated and measured concentration changes of phenol treated and intermediates produced in UV/TiO2 system 68

Anpo, M., Shima, T., Kodama, S., Kubokawa, Y., 1987. Photocatalytic hydrogenation of CH3CCH with H2O on small-particle TiO2: size quantization effects and reaction intermediates. J. Phys. Chem. 91, 4305-4310.
Al-Ekabi, H., Serpone, N., 1989. Kinetic studies in heterogeneous photocatalysis. 2. TiO2-mediated degradation of 4-chlorophenol alone and in a three-component mixture of 4-chlorophenol, 2,4-dichlorophenol, and 2,4,5-trichlorophenol in air-equilibrated aqueous media. Langmuir 5, 250-255.
Anderson, M.A., Yamazaki-Nishida, S., Cervera-March, S., 1993. Photodegradation of trichloroethylene in the gas phase using TiO2 porous ceramic membrane. In: Ollis, D.F., Al-Ekabi, H. (Eds.). Photocatalytic Purification and Treatment of Water and Air. Elsevier, pp. 405-420.
Andreozzi, R., Caprio, V., Insola, A., Marotta, R., 1999. Advanced oxidation processes (AOP) for water purification and recovery. Catal. Today 53, 51-59.
Anpo, M., 2000. Utilization of TiO2 photocatalysts in green chemistry. Pure Appl. Chem. 72, 1265-1270.
Almquist, C.B., Biswas, P., 2002. Role of synthesis method and particle size of nanostructured TiO2 on its photoactivity. J. Catal. 212, 145-156.
Andersson, M., Österlund, L., Ljungström, S., Palmqvist, A., 2002. Preparation of nanosize anatase and rutile TiO2 by hydrothermal treatment of microemulsions and their activity for photocatalytic wet oxidation of phenol. J. Phys. Chem. B 106, 10674-10679.
Azevedo, E.B., Radler de Aquino Neto, F., Dezotti, M., 2004. TiO2-photocatalyzed degradation of phenol in saline media: lumped kinetics, intermediates, and acute toxicity. Appl. Catal. B: Environ. 54, 165-173.
Bhore, N.A., Klein, M.T., Bischoff, K.B., 1990. The delplot technique: a new method for reaction pathway analysis. Ind. Eng. Chem. Res. 29, 313-316.
Balcioglu, I.A., Arslan, I., 1998. Application of photocatalytic oxidation treatment to pretreated and raw effluents from the Kraft bleaching process and textile industry. Environ. Pollution 103, 261-268.
Boujday, S., Wünsch, F., Portes, P., Bocquet, J.-F., Colbeau-Justin, C., 2004. Photocatalytic and electronic properties of TiO2 powders elaborated by sol-gel route and supercritical drying. Sol. Energ. Mat. Sol. C. 83, 421-433.
Chan, A.H.C., Chan, C.K., Barford, J.P., Porter, J.F., 2003. Solar photocatalytic thin film cascade reactor for treatment of benzoic acid containing wastewater. Water Res. 37, 1125-1135.
Colόn, G., Hidalgo, M.C., Navío, J.A., 2003. Photocatalytic behaviour of sulphated TiO2 for phenol degradation. Appl. Catal. B: Environ. 45, 39-50.
Carpio, E., Zúñiga, P., Ponce, S., Solis, J., Rodriguez, J., Estrada, W., 2004. Photocatalytic degradation of phenol using TiO2 nanocrystals supported on activated carbon. J. Mol. Catal. A: Chem. 228, 293-298.
Cheng, Y., Sun, H., Jin, W., Xu, N., 2007. Photocatalytic degradation of 4-chlorophenol with combustion synthesized TiO2 under visible light irradiation. Chem. Eng. J. 128, 127-133.
Dosanjh, M.K., Wasa, D.A.J., 1987. Oxygen uptake studies on various sludge adaption to a waste containing chloro-, nitro-, and amino-substituted xenobiotics. Water Res. 21, 205-209.
Draper, R.B., Fox, M.A., 1990. Titanium dioxide photosensitized reactions studied by diffuse reflectance flash photolysis in: aqueous suspensions of TiO2 powder. Langmuir 6, 1396-1402.
Döker, O., Bayraktar, E., Mehmetoğlu, Ü., Çalimli, A., 2003. Production of iron-cobalt compound nanoparticles using reverse micellar system. Rev. Adv. Mater. Sci. 5, 498-500.
Dunn, J.B., Savage, P.E., 2005. High-temperature liquid water: a viable medium for terephthalic acid synthesis. Environ. Sci. Technol. 39, 5427-5435.
Du, Y., Zhou, M., Lei, L., 2007. Kinetic model of 4-CP degradation by Fenton/O2 system. Water Res. 41, 1121-1133.
Emeline, A.V., Serpone, N., 2002. Spectral selectivity of photocatalyzed reactions occurring in liquid-solid photosystems. J. Phys. Chem. B: 106, 12221-12226.
Fujishima, A., Honda, K., 1972. Electrochemical photolysis of water at a semiconductor electrode. Nature 238, 37-38.
Fujishima, A., Hashimoto, K., Watanabe, T., 1999. TiO2 photocatalysis fundamentals and applications. BKC, Tokyo.
Fujishima, A., Rao, T.N., Tryk, D.A., 2000. Titanium dioxide photocatalysis. J. Photoch. Photobio. C 1, 1-21.
Gimeno, O., Carbajo, M., Beltrán, F.J., Rivas, F.J., 2005. Phenol and substituted phenols AOPs remediation. J. Hazard. Mater. B119, 99-108.
Guo, Z., Ma, R., Li, G., 2006. Degradation of phenol by nanomaterial TiO2 in wastewater. Chem. Eng. J. 119, 55-59.
Herrmann, J.-M., 1999. Heterogeneous photocatalysis: fundamentals and applications to the removal of various types of aqueous pollutants. Catal. Today 53, 115-129.
Herrmann, J.-M., Guillard, C., Disdier, J., Lehaut, C., Malato, S., Blanco, J., 2002. New industrial titania photocatalysts for the solar detoxification of water containing various pollutants. Appl. Catal. B: Environ. 35, 281-294.
Hong, S.S., Lee, M.S., Park, S.S., Lee, G.-D., 2003. Synthesis of nanosized TiO2/SiO2 particles in the microemulsion and their photocatalytic activity on the decomposition of p-nitrophenol. Catal. Today 87, 99-105.
Jardim, W.F., Moraes, S.G., Takiyama, M.M.K., 1997. Photocatalytic degradation of aromatic chlorinated compounds using TiO2: toxicity of intermediates. Water Res. 31, 1728-1732.
Jang, H.D., Kim, S.-K., Kim, S.-J., 2001. Effect of particle size and phase composition of titanium dioxide nanoparticles on the photocatalytic properties. J. Nanopart. Res. 3, 141-147.
Jiang, B., Yin, H., Jiang, T., Yan, J., Fan, Z., Li, C., Wu, J., and Wada, Y., 2005. Size-controlled synthesis of anatase TiO2 nanopparticles by carboxylic acid group-containing organics. Mater. Chem. Phys. 92, 595-599.
Kormann, C., Bahnemann, D.W., Hoffmann, M.R., 1988. Preparation and characterization of quantum-size titanium-dioxide. J. Phys. Chem. 92, 5196-5201.
Ku, Y., Hsieh, C.B., 1992. Photocatalytic decomposition of 2,4-dichlorophenol in aqueous TiO2 suspensions. Water Res. 26, 1451-1456.
Kumar, P., Mittal, K.L., 1999. Handbook of Microemulsion Science and Technology. Mercel Dekker: New York.
Kolen’ko, Y.V., Churagulov, B.R., Kunst, M., Mazerolles, L., Colbeau-Justin, C., 2004. Photocatalytic properties of titania powders prepared by hydrothermal method. Appl. Catal. B: Environ. 54, 51-58.
Linsebigler, A.L., Lu, G., Yates Jr., J.T., 1995. Photocatalysis on TiO2 surfaces: principles, mechanisms, and selected results. Chem. Rev. 95, 735-758.
Low, G.K.-C., McEvoy, S.R., 1996. Analytical monitoring systems based on photocatalytic oxidation principles. TrAC Trend. Anal. Chem. 15, 151-156.
Lachheb, H., Puzenat, E., Houas, A., Ksibi, M., Elaloui, E., Guillard, C., Herrmann, J.-M., 2002. Photocatalytic degradation of various types of dyes (Alizarin S, Crocein Orange G, Methyl Red, Congo Red, Methylene Blue) in water by UV-irradiated titania. Appl. Catal. B: Environ. 39, 75-90.
Liu, G., Li, X., Zhao, J., Horikoshi, S., Hidaka, H., 2000. Photooxidation mechanism of dye alizarin red in TiO2 dispersions under visible illumination: an experimental and theoretical examination. J. Mol. Catal. A: Chem. 153, 221-229.
Liu, D., Zhang, J., Han, B., Chen, J., Li, Z., Shen, D., and Yang, G., 2003. Recovery of TiO2 nanoparticles synthesized in reverse micelles by antisolvent CO2. Colloid Surface A227, 45-48.
Li, G., Li, L., Boerio-Goates, J., Woodfield, B.F., 2005. High purity anatase TiO2 nanocrystals: near room-temperature synthesis, grain growth kinetics, and surface hydration chemistry. J. Am. Chem. Soc. 127, 8659-8666.
Lin, H., Huang, C.P., Li, W., Ni, C., Shah, S.I., Tseng, Y.-H., 2006. Size dependency of nanocrystalline TiO2 on its optical property and photocatalytic reactivity exemplified by 2-chlorophenol. Appl. Catal. B: Environ. 68, 1-11.
Matthews, R., 1984. Hydroxylation reactions induced by near-ultraviolet photolysis of aqueous titanium dioxide suspensions. J. Chem. Soc. Farad. T. 80, 457-471.
Mills, G., Hoffmann, M.R., 1993. Photocatalytic degradation of pentachlorophenol on TiO2 particles: identification of intermediates and mechanism of reaction. Environ. Sci. Technol. 27, 1681-1689.
Moran, P.D., Bartlett, J.R., Bowmaker, G.A., Woolfrey, J.L., Cooney, R.P., 1999. Formation of TiO2 sols, gels and nanopowders from hydrolysis of Ti(OiPr)4 in AOT reverse micelles. J. Sol-Gel Sci. Techn. 15, 251-262.
Maira, A.J., Yeung, K.L., Lee, C.Y., Yue, P.L., Chan, C.K., 2000. Size effects in gas-phase photo-oxidation of trichloroethylene using nanometer-sized TiO2 catalysts. J. Catal. 192, 185-196.
Minero, C., Mariella, G., Maurino, V., Pelizzetti, E., 2000. Photocatalytic transformation of organic compounds in the presence of inorganic anions. 1. hydroxyl-mediated and direct electron-transfer reactions of phenol on a titanium dioxide-fluoride system. Langmuir 16, 2632-2641.
Mori, Y., Okastu, Y., Tsujimoto, Y., 2001. Titanium dioxide nanoparticles produced in water-in-oil emulsion. J. Nanopart. Res. 3, 219, 219-225.
Malato, S., Blanco, J., Cáceres, J., Fernández-Alba, A.R., Agüera, A., Rodríguez, A., 2002. Photocatalytic treatment of water-soluble pesticides by photo-Fenton and TiO2 using solar energy. Catal. Today 76, 209-220.
Malato, S., Blanco, J., Vidal, A., Fernández, P., Cáceres, J. Trincado, P., Oliveira, J.C., Vincent, M., 2002. New large solar photocatalytic plant: set-up and preliminary results. Chemosphere 47, 235-240.
Malato, S., Blanco, J., Vidal, A., Richter, C., 2002. Photocatalytic with solar energy at a pilot-plant scale: an overview. Appl. Catal. B: Environ. 37, 1-15.
Malato, S., Blanco, J., Vidal, A., Alarcón, D., Maldonado, M.I., Cáceres, J., Gernjak, W., 2003. Applied studies in solar photocatalytic detoxification: an overview. Sol. Energy 75, 329-336.
Muruganandham, M., Shobana, N., Swaminathan, M., 2005. Optimization of solar photocatalytic degradation conditions of reactive Yellow 14 azo dye in aqueous TiO2. J. Mol. Catal. A: Chem. 246, 153-160.
Nargiello, M., Herz, T., 1993. Physical-chemical characteristics of P-25 making it suited as the catalyst in photodegradation of organic compounds. In: Ollis, D.F., Al-Ekabi, H. (Eds.). Photocatalytic Purification and Treatment of Water and Air. Elsevier, pp. 801-807.
Natarajan, S., Olson, W.W., Abraham, M.A., 2000. Reaction pathways and kinetics in the degradation of forging lubricants. Ind. Eng. Chem. Res. 39, 2837-2842.
Nagaveni, K., Hegde, M.S., Ravishankar, N., Subbanna, G.N., and Madras, G., 2004. Synthesis and structure of nanocrystalline TiO2 with lower band gap showing high photocatalytic activity. Langmuir 20, 2900-2907.
Nagaveni, K., Sivalingam, G., Hegde, M.S., Madras, G., 2004. Photocatalytic degradation of organic compounds over combustion-synthesized nano-TiO2. Environ. Sci. Technol. 38, 1600-1604.
Nagaveni, K., Sivalingam, G., Hegde, M.S., Madras, G., 2004. Solar photocatalytic degradation of dyes: high activity of combustion synthesized nano TiO2. Appl. Catal. B: Environ. 48, 83-93.
Nahar, M.S., Hasegawa, K., Kagaya, S., 2006. Photocatalytic degradation of phenol by visible light-responsive iron-doped TiO2 and spontaneous sedimentation of the TiO2 particles. Chemosphere 65, 1976-1982.
O'Donoghue, M., 1983. A guide to Man-made Gemstones (in english). Great Britain: Van Nostrand Reinhold Company, 40–44.
Ollis, F., Pelizzetti, E., Serpons, N., 1991. Destruction of water contaminants. Environ. Sci. Technol. 25, 1523-1529.
Ollis, D.F., Al-Ekabi, H., 1993. eds. Photocatalytic purification and treatment of water and air. Elsevier, Amsterdam.
Ohno, T., Akiyoshi, M., Umebayashi, T., Asai, K., Mitsui, T., Matsumura, M., 2004. Preparation of S-doped TiO2 photocatalysts and their photocatalytic activities under visible light. Appl. Catal. A: Gen. 265, 115–121.
Okamoto, K., Yamamoto, Y., Tanaka, H., Tanaka, M., 1985. Heterogeneous photocatalytic decomposition of phenol over TiO2 powder. Bull. Chem. Soc. Jpn. 58, 2015-2022.
Ormad, M.P., Ovelleiro, J.L., Kiwi, J., 2001. Photocatalytic degradation of concentrated solutions of 2,4-dichlorophenol using low energy light identification of intermediates. Appl. Catal. B: Environ. 32, 157-166.
Park, H.K., Kim, D.K., Kim, C.H., 1997. Effect of solvent on titania particle formation and morphology in thermal hydrolysis of TiCl4. J. Am. Ceram. Soc. 80, 743-749.
Rivera, A.P., Tanaka, K., Hisanaga, T., 1993. Photocatalytic degradation of pollutant over TiO2 in different crystal structures. Appl. Catal. B: Environ. 3, 37-44.
Romero, M., Blanco, J., Sánchez, B., Vidal, A., Malato, S., Cardona, A.I., Garcia, E., 1999. Solar photocatalytic degradation of water and air pollutants: challenges and perspectives. Sol. Energy 66, 169-182.
Rachel, A., Subrahmanyam, M., Boule, P., 2002. Comparison of photocatalytic efficiencies of TiO2 in suspended and immobilized form for the photocatalytic degradation of nitrobenzenesulfonic acids. Appl. Catal. B: Environ. 37, 301-308.
Serpone, N., Lawless, D., Khairutdinov, R., 1995. Size effects on the photophysical properties of colloidal anatase TiO2 particles. J. Phys. Chem. 99, 16646-16654.
Shinoda, K., Friberg, S., 1986. Emulsions and solubilization. New York: Wiley, pp. 16.
Stefan, M.I., Bolton, J.R., 1998. Mechanism of the degradation of 1,4-dioxane in dilute aqueous solution using the UV/Hydrogen peroxide process. Environ. Sci. Technol. 32, 1588-1595.
Saha, N.C., Bhunia, F., Kaviraj, A., 1999. Toxicity of phenol to fish and aquatic ecosystems. Bull. Environ. Contam. Toxicol. 63, 195-202.
Sun, B., Vorontsov, A.V., Smirniotis, P.G., 2003. Role of platinum deposited on TiO2 in phenol photocatalytic oxidation. Langmuir 19, 3151-3156.
Sivalingam, G., Nagaveni, K., Hegde, M.S., Madras, G., 2003. Photocatalytic degradation of various dyes by combustion synthesized nano anatase TiO2. Appl. Catal. B: Environ. 45, 23-38.
Sobczyński, A., Duczmal, Ł., Zmudziński, W.J., 2004. Phenol destruction by photocatalysis on TiO2: an attempt to solve the reaction mechanism. J. Mol. Catal. A: Chem. 213, 225-230.
Santos, A., Yustos, P., Quintanilla, A., García-Ochoa, F., Casas, J.A., Rodríguez, J.J., 2004. Evolution of toxicity upon wet catalytic oxidation of phenol. Environ. Sci. Technol. 38, 133-138.
Sui, X., Chu, Y., Xing, S., Yu, M., Liu, C., 2004. Self-organization of spherical PANI/TiO2 nanocomposites in reverse micelles. Colloid Surface A 251, 103-107.
Turchi, C.S., Ollis, D.F., 1990. Photocatalytic degradation of organic water contaminants: mechanisms involving hydroxyl radical attack. J. Catal. 122, 178-192.
Thornton, T.D., Savage, P.E., 1992. Phenol oxidation pathways in supercritical water. Ind. Eng. Chem. Res. 31, 2451-2456.
Theurich, J., Lindner, M., Bahnemann, D.W., 1996. Photocatalytic degradation of 4-chlorophenol in aerated aqueous titanium dioxide suspensions: a kinetic and mechanistic study. Langmuir 12, 6368-6376.
Tišler, T., Zagorc-Končan, J., 1997. Comparative assessment of toxicity of phenol, formaldehyde, and industrial wastewater to aquatic organisms. Water Air Soil Poll. 97, 315-322.
Vorkapic, D., Matsoukas, T., 1998. Effect of temperature and alcohols in the preparation of titania nanoparticles from alkoxides. J. Am. Ceram. Soc. 81, 2815-2820.
Vautier, M., Guillard, C., Herrmann, J.-M., 2001. Photocatalytic degradation of dyes in water: case study of indigo and of indigo carmine. J. Catal. 201, 46-59.
Wu, J., 1999. The fineness of ATH and its application in nonhalogen flame retardant technique. Chem. Ind. Eng. Prog., 2, http://www.dfmg.com.tw/liture/china/% A4% C6%A4u% B6i%AEi/990215.htm, visited in August 2006.
Wang, C.-C., Zhang, Z., Ying, J.Y., 1997. Photocatalytic decomposition of halogenated organics over nanocrystalline titania. Nanostruct. Mater. 9, 583-586.
Wang, W., Serp, P., Kalck, P., Luís Faria, J., 2004. Photocatalytic degradation of phenol on MWNT and titania composite catalysts prepared by a modified sol-gel method. Appl. Catal. B: Environ. 56, 305-312.
Yeber, M.C., Rodríguez, J., Freer, J., Baeza, J., Durán, N., Mansilla, H.D., 1999. Advanced oxidation of a pulp mill bleaching wastewater. Chemosphere 39, 1679-1688.
Yuan, G., Keane, M.A., 2003. Liquid phase catalytic hydrodechlorination of 2,4-dichlorophenol over carbon supported palladium: an evaluation of transport limitations. Chem. Eng. Sci. 58, 257-267.
Yang, G.-J., Li, C.-J., Han, F., Ohmori, A., 2004. Microstructure and photocatalytic performance of high velocity oxy-fuel sprayed TiO2 coatings. Thin Solid Films 466, 81-85.
Zhang, D., Qi, L., Ma, J., Cheng, H., 2002. Formation of crystalline nanosized titania in reverse micelles at room temperature. J. Mater. Chem. 12, 3677-3680.
Zhu, H.Y., Li, J.-Y., Zhao, J.-C., Churchman, G.J., 2004. Photocatalysts prepared from layered clays and titanium hydrate for degradation of organic pollutants in water. Appl. Clay Sci. 28, 79-88.
Zazo, J.A., Casas, J.A., Mohedano, A.F., Gilarranz, M.A., Rodríguez, J.J., 2005. Chemical pathway and kinetics of phenol oxidation by fenton’s reagent. Environ. Sci. Technol. 39, 9295-9302.