Titanium dioxide nanoparticles (TiO2-NP) are one of the most abundantly utilized nanomaterials in the world. Studies have demonstrated the mechanism of acute toxicity in TiO2-NP to be the production of reactive oxygen species (ROS) leading to oxidative stress and mortality in exposed organisms. It has also been demonstrated that the anatase crystalline conformation is capable of catalyzing the cleavage of water molecules to further increase the concentration of ROS in the presence of ultraviolet radiation. This photoenhanced toxicity significantly lowers the toxicity threshold of TiO2-NP to environmentally relevant concentrations (ppb). The goal of this study was to determine whether dietary uptake and accumulation of TiO2-NP in the aquatic filter feeder Daphnia magna resulted in photoenhanced toxicity. D. magna and S. caprincornatum were exposed to aqueous solutions of 20ppm and 200ppm TiO2-NP for 24hrs and then transferred to clean moderately hard water. Samples were taken at various time points, dried, and TiO2 quantified using ICP-MS. Toxicity assays were run on D. magna using three TiO2-NP (20ppm, 200ppm) exposure protocols and two ultraviolet radiation treatments. The first exposure group was exposed to aqueous solutions of TiO2-NP for the duration of the test. The second exposure group was exposed to TiO2-NP for an hour and then transferred to clean water. The third exposure group was fed S. capricornatum that had been allowed to adsorb TiO2-NP. All samples were then placed in an outdoor UV exposure system and exposed to either full spectrum sunlight (with UV) or filtered sunlight (no UV). Here we show that TiO2 uptake peaked at one hour of exposure likely due to sedimentation of the particles out of suspension, thus decreasing bioavailability for the duration of the test. Interetsingly, when D. magna were moved to clean water, aqueous concentrations of TiO2 increase as a result of depuration from the gut tract. Data also suggests these excreted particles were bioavailable and re-consumed by D. magna. These data will contribute to the understanding of TiO2-NP environmental fate and toxicity.

Li, Chuanhao. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Cheng, Kai Hong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 134-141). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iv / Table of Contents --- p.v / List of Figures --- p.viii / List of Tables --- p.xix / Chapter iii. --- Table of Contents / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Semiconductor spintronics --- p.1 / Chapter 1.1.1 --- Overview --- p.1 / Chapter 1.2 --- Dilute magnetic semiconductors (DMS) --- p.2 / Chapter 1.2.1 --- Historical background --- p.3 / Chapter 1.2.2 --- Their importance and significance --- p.4 / Chapter 1.2.3 --- Material systems showing room temperature ferromagnetism --- p.5 / Chapter 1.3 --- Cobalt (iron)-doped titanium dioxide as DMS --- p.7 / Chapter 1.3.1 --- Structures and properties of titanium dioxide --- p.8 / Chapter 1.3.2 --- Various preparation techniques of cobalt (iron)-doped titanium dioxide --- p.10 / Chapter 1.3.3 --- This thesis --- p.13 / Chapter Chapter 2 --- Sample Preparation and Characterization Techniques --- p.14 / Chapter 2.1 --- Sample preparation --- p.14 / Chapter 2.1.1 --- RF magnetron sputtering --- p.14 / Chapter 2.1.2 --- MEVVA ion implantation --- p.17 / Chapter 2.1.3 --- Sample preparation conditions --- p.19 / Chapter 2.2 --- Characterization techniques --- p.24 / Chapter 2.2.1 --- Structural characterization --- p.24 / Chapter 2.2.1.1 --- Rutherford backscattering spectrometry (RBS) --- p.24 / Chapter 2.2.1.2 --- X-ray diffraction (XRD) --- p.26 / Chapter 2.2.1.3 --- X-ray photoelectron spectroscopy (XPS) --- p.28 / Chapter 2.2.1.4 --- Transmission electron microscopy (TEM) --- p.31 / Chapter 2.2.2 --- Vibrating sample magnetometry (VSM) --- p.33 / Chapter 2.2.3 --- Temperature varying resistivity measurements --- p.35 / Chapter Chapter 3 --- Characterization of Titanium Dioxide Samples --- p.40 / Chapter 3.1 --- RBS results --- p.40 / Chapter 3.2 --- XRD results --- p.43 / Chapter 3.3 --- XPS results --- p.47 / Chapter 3.4 --- Summary --- p.51 / Chapter Chapter 4 --- Characterization of Cobalt-implanted Titanium Dioxide Sample --- p.53 / Chapter 4.1 --- Cobalt dose dependence --- p.53 / Chapter 4.1.1 --- RBS results --- p.53 / Chapter 4.1.2 --- XRD results --- p.65 / Chapter 4.1.3 --- VSM results --- p.69 / Chapter 4.1.4 --- Temperature varying resistivity measurements --- p.75 / Chapter 4.2 --- Effects of annealing temperature --- p.77 / Chapter 4.2.1 --- RBS results --- p.77 / Chapter 4.2.2 --- XRD results --- p.79 / Chapter 4.2.3 --- XPS results --- p.83 / Chapter 4.2.4 --- TEM results --- p.88 / Chapter 4.2.5 --- VSM results --- p.91 / Chapter 4.2.6 --- Temperature varying resistivity measurements --- p.97 / Chapter 4.3 --- Summary --- p.99 / Chapter Chapter 5 --- Characterization of Iron-implanted Titanium Dioxide Samples --- p.101 / Chapter 5.1 --- Iron dose dependence --- p.101 / Chapter 5.1.1 --- RBS results --- p.101 / Chapter 5.1.2 --- XRD results --- p.107 / Chapter 5.1.3 --- VSM results --- p.110 / Chapter 5.1.4 --- Temperature varying resistivity measurements --- p.114 / Chapter 5.2 --- Effects of annealing temperature --- p.116 / Chapter 5.2.1 --- RBS results --- p.116 / Chapter 5.2.2 --- XRD results --- p.117 / Chapter 5.2.3 --- VSM results --- p.119 / Chapter 5.2.4 --- Temperature varying resistivity measurements --- p.121 / Chapter 5.3 --- Summary --- p.122 / Chapter Chapter 6 --- Conclusion and future work --- p.125 / Appendices --- p.127 / Bibliography --- p.134 / Publications --- p.141 / Chapter iv. --- List of Figures / Fig. 1.1 Crystal structures for two most stable polymorphs of TiO2: (a) anatase; and (b) rutile --- p.9 / Fig. 2.1 Schematic of RF sputtering system --- p.15 / Fig. 2.2 Motion of electrons emitted for the target surface (a) in the applied magnetic field (-z direction); (b) in the applied electric field (-y direction) and magnetic field (-z direction) --- p.16 / Fig. 2.3 Schematic of the implanter with the MEVVA ion source --- p.17 / Fig. 2.4 The TRIM ion distribution profile of Co atoms in anatase TiO2 by implantation to a Co dose of 2.2 x 1016 cm-2 at an extraction voltage of 65 kV --- p.21

In addition, through a simple post-thermal treatment of TiO2 thin films on glass with trifluoroacetic acid (TFA), the thin films showed enhancement in the photocatalytic decomposition of acetone in air. XPS, FTIR and PL results revealed that the TFA complex bound on the surface of TiO 2 acted as an electron scavenger, and thus reduced the recombination of photo-generated electrons and holes. / Part I. TiO2 films on stainless steel prepared by dip coating in a nonionic microemulsion solution were investigated. These thin films have been shown to have much higher photocatalytic activity than films on glass substrates. XPS showed that Fe3+ and Fe 2+ ions, which were diffused from stainless steel substrate into TiO 2 films during high temperature calcination, behaved as dopants to significantly affect its photocatalytic activity of the films. The TiO2 films also exhibited excellent photo-induced hydrophilicity and antibacterial effect on the sterilization of Bacillus pumilus. / Part II. New approaches have been developed for the fabrication of visible light photocatalysts. MoS2 and WS2 were coupled to TiO2 by an in situ photo-reduction deposition method, taking advantage of the reducing power of TiO2 particles. The synthesis of CdSe sensitized TiO2 using an ultrasound-driven approach was also reported. The photocatalytic degradation of methylene blue and 4-chlorophenol was employed to evaluate their visible light photocatalytic activity. The small band gap semiconductors acting as photo-sensitizers not only extended the spectral response of TiO2 to the visible region but also improved their photocatalytic efficiency. The blue shift in the absorption onset confirmed the size-quantization of photosensitizers, which altered the conduction and valence band levels in the coupled semiconductor systems making it possible to utilize visible light in photocatalysis. (Abstract shortened by UMI.) / Two important aspects of the TiO2 photocatalysis were studied in this thesis. The first part reports on the improvement of photocatalytic performance of TiO2 films through approaches such as post-thermal treatment, surface modification and metal doping. The second part describes the fabrication of visible light TiO2 photocatalyts by means of coupling with small band gap semiconductor photo-sensitizers and non-metal doping. / Ho Wing-kei. / "May 2005." / Adviser: Jimmy C. Yu. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0294. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Ding, Zhimin = 遺態二氧化鈦的製備和表徵及其在光催化中的性能分析 / 丁志敏. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Abstracts in English and Chinese. / Ding, Zhimin = Yi tai er yang hua tai de zhi bei he biao zheng ji qi zai guang cui hua zhong de xing neng fen xi / Ding Zhimin. / ABSTRACT --- p.i / 摘要 --- p.iii / Acknowledgement --- p.v / Table of Contents --- p.vi / List of Figures --- p.ix / List of Tables --- p.xiii / Chapter Chpater 1 --- Introduction --- p.1 / Chapter 1.1 --- Titanium dioxide --- p.1 / Chapter 1.1.1 --- Lattice structure --- p.2 / Chapter 1.1.2 --- Phase transition --- p.3 / Chapter 1.1.3 --- Energy band structure --- p.4 / Chapter 1.1.3.1 --- Band structure of titanium dioxide --- p.4 / Chapter 1.1.3.2 --- Quantum size effect --- p.6 / Chapter 1.1.4 --- Principle of photocatalysis --- p.8 / Chapter 1.1.5 --- Improvement of the TiO2 photocatalyst --- p.10 / Chapter 1.1.5.1 --- Noble metal deposition --- p.10 / Chapter 1.1.5.2 --- Coiq)led semiconductor --- p.11 / Chapter 1.1.5.3 --- Ion doping --- p.12 / Chapter 1.2 --- Biomorphic materials --- p.13 / Chapter 1.3 --- Cotton template --- p.14 / Chapter 1.3.1 --- Composition of cotton --- p.14 / Chapter 1.3.2 --- Cotton structure --- p.15 / Chapter 1.4 --- Methyl orange --- p.16 / Chapter 1.5 --- Objectives and thesis layout --- p.18 / References --- p.19 / Chapter Chapter 2 --- Methodology and Instrumentation --- p.27 / Chapter 2.1 --- Sample preparation --- p.27 / Chapter 2.1.1 --- Template and precursors --- p.27 / Chapter 2.1.2 --- Synthesis of the Ti02-TTIP samples --- p.28 / Chapter 2.1.2.1 --- Methodology --- p.28 / Chapter 2.1.2.2 --- Fabrication procedures --- p.31 / Chapter 2.1.3 --- Synthesis of the TiO2-TALH samples --- p.32 / Chapter 2.1.3.1 --- Methodology --- p.32 / Chapter 2.1.3.2 --- Fabrication procedures --- p.33 / Chapter 2.2 --- Characterization --- p.33 / Chapter 2.2.1 --- Scanning electron microscope (SEM) --- p.33 / Chapter 2.2.2 --- Transmission electron microscope (TEM) --- p.34 / Chapter 2.2.3 --- Raman spectroscopy (RS) --- p.34 / Chapter 2.2.4 --- X-ray diffractometry (XRD) --- p.34 / Chapter 2.2.5 --- Thermo gravimetric analysis (TGA) --- p.35 / Chapter 2.2.6 --- Differential thermal analysis (DTA) --- p.36 / Chapter 2.2.7 --- Ultraviolet-visible spectroscopy (UV-vis) --- p.36 / Chapter 2.3 --- Photocatalytic performance --- p.37 / Chapter 2.3.1 --- Lambert-Beer's law --- p.37 / Chapter 2.3.2 --- "Verification of Beer,s Law" --- p.38 / Chapter 2.3.3 --- Photocatalytic evaluation procedures --- p.39 / Chapter 2.3.3.1 --- Glass beaker --- p.39 / Chapter 2.3.3.2 --- Quartz vessel --- p.40 / References --- p.41 / Chapter Chapter 3 --- Results of Characterizations --- p.43 / Chapter 3.1 --- Characterization of Ti02-TTIP --- p.43 / Chapter 3.1.1 --- Effect of calcination temperature on the samples --- p.43 / Chapter 3.1.1.1 --- DTA and TGA results --- p.43 / Chapter 3.1.1.1.1 --- Pure cotton --- p.43 / Chapter 3.1.1.1.2 --- Sol-infiltrated cotton --- p.45 / Chapter 3.1.1.2 --- XRD results --- p.47 / Chapter 3.1.1.3 --- Raman spectra results --- p.51 / Chapter 3.1.1.4 --- SEM results --- p.54 / Chapter 3.1.2.5 --- TEM results --- p.58 / Chapter 3.1.1.6 --- UV-visible absorption spectra --- p.60 / Chapter 3.1.2 --- Effect of calcination duration on the properties of samples --- p.61 / Chapter 3.1.2.1 --- XRD results --- p.62 / Chapter 3.1.2.2 --- Raman spectra results --- p.65 / Chapter 3.2 --- Characterization ofTiO2 -TALH --- p.67 / Chapter 3.2.1 --- DTA and TGA results --- p.67 / Chapter 3.2.2 --- XRD results --- p.69 / Chapter 3.2.3 --- Raman spectra results --- p.72 / Chapter 3.2.4 --- SEM results --- p.73 / Chapter 3.2.5 --- TFM rpcnltc --- p.76 / Chapter 3.2.6 --- UV-visible absorption spectra --- p.78 / References --- p.79 / Chapter Chapter 4 --- Photocatalytic Performance --- p.81 / Chapter 4.1 --- Verification of Beer's Law --- p.81 / Chapter 4.2 --- Photocatalytic results --- p.82 / Chapter 4.2.1 --- MO solution contained by glass beaker --- p.83 / Chapter 4.2.2 --- MO solution contained by quartz vessel --- p.86 / Chapter 4.2.3 --- Photocatalytic performance of TiO2-TALH sample prepared at 600°C --- p.90 / Chapter 4.3 --- Discussions --- p.92 / References --- p.94 / Chapter Chapter 5 --- Conclusions and Future Works --- p.95 / Chapter 5.1 --- Conclusions --- p.95 / Chapter 5.2 --- Future works --- p.98 / References --- p.99

Graduation date: 1996

Thesis (Ph. D.)--Oregon Graduate Center, 1982.

Anodized aluminium oxide may be chemically treated to yield a uniform self-organized distribution of pores with a specific pore diameter. The thickness of in-house anodized alumina and its pore size can be modified by changing the electrolyte, the temperature of the electrolyte, the time of anodization and the potential over the anodized plates.  In this thesis, a method for anodized aluminium oxide (AAO) was optimized for creating custom-made porous alumina membranes and coating them with TiO2 and polyethylene glycol (PEG). The purpose of finding a method to create porous alumina oxide with specific pore diameters was to eventually use these membranes for use in contact with human living tissue, allowing wanted nutrients and fluid to pass in and out.      SEM images showed that a reproducible method has been established for the membrane production, where the pore diameter is ~ 300nm and the thickness of the oxide is approximately 100µm. The SEM images also showed that the pores are stable and uniform over the entire aluminum plate where they are initially produced.      As a test for biocompatibility, the membranes were implanted into the hipbone of pigs. The histology test showed fibrosis around the location where the membranes were placed. An observation during the extraction was swollenness in the surrounding tissue, which indicates inflammation around the implant. In this respect, the membranes cannot be used for the purpose intended.

No description available.

Thesis (Ph.D.)--North Carolina State University, 2008. / Adviser: Ollis, David F. Includes bibliographical references.