There is a need to develop techniques for conversion of carbon dioxide to other useful products such as methanol, formaldehyde, formic acid, formate, methane, and hydrocarbons. Carbon dioxide can be converted into these products using different methods such as photochemical, electrochemical, thermochemical and hydrogenation by bacteria. Formate is of interest due to its wide industrial applications which include it’s use in direct liquid fuel cells, as an additive in pyrolysis vapors, a precursor for biological fuels, and it is a key intermediate in methanogenesis breaking down complex organic compounds. In this work, conversion of carbon dioxide to formate was accomplished photochemically. The concentration of formate obtained was quantified using ion chromatography. The yield of formate, based on the amount of carbon dioxide in solution, was 1.54%, while the quantum yield was near 2.0%. Detailed studies of the photoreduction process showed that the amount of sensitizer, light intensity and pH affect the amount of formate generated.

Highly dispersed gold nanoparticles on metal oxide surfaces have recently been reported to exhibit high catalytic activity for low-temperature carbon monoxide oxidation. Amongst the metal oxides, titanium dioxide, more often the commercial form Degussa P25, has been the most studied support for gold as a catalyst for CO oxidation because it yields some of the most active and stable catalysts. Physical and chemical modification of catalysts supports has been shown to affect their catalytic properties. In this research, modified gold supported catalysts have been prepared, characterized and tested for CO oxidation. Their properties have been compared with those of the unmodified catalysts. Catalysts containing1wt% Au supported on MxOy and TiO2/MxOy mixed oxide (M = Zn, Mg, Ni, Fe, Cr, Cu, Mn and Co; TiO2:MxOy mole ratio of 5:1; TiO2 = Degussa P25) were prepared by the single step borohydride reduction method and it was found that TiO2 gave the most superior activity as support for gold for CO oxidation, followed by TiO2/MxOy and the corresponding MxOy. The specific activities for CO oxidation of Au/TiO2 catalysts per unit of prepared in the range 0.05 to 1 wt% of Au indicates that for catalysts prepared by deposition precipitation, there is a significant decrease in specific activities with an increase with gold loading. For the single step borohydride reduction procedure, specific activities decrease less significantly with increasing gold content, implying that for economic and practical reasons, it would be advantageous to prepare gold catalysts with low gold loadings. Cyanide leaching of 1 wt% Au/TiO2 catalysts at different Au:CN- ratios, to selectively remove some of the gold in the catalysts, shows the activity per unit mass of gold to increases as more gold is removed from the catalyst. This is consistent with the idea that gold exists in more than one oxidation state in the systems and a significant fraction of the gold present in the catalysts do not contribute to catalytic activity. A number of anions and cations have been incorporated into TiO2 as support for gold catalysts and also into as-prepared Au/TiO2 catalysts at levels ranging from 0.05 mol% to 2.5 mol% with respect to the support. The activities of the catalysts for CO oxidation reveal that at the highest concentration levels of the ions, in all cases, a decrease in activity compared with unmodified Au/TiO2 is observed. However, addition of 0.05 to 0.4 mol% of the ions with respect to the support, prior to gold addition, in most cases, resulted in activity enhancement which increased with a decrease in the ion content. Similar addition of 0.05 to 0.4 mol% of the ions with respect to TiO2 to Au/TiO2 resulted in a decrease in activity. Attempts to understand the origins of these effects show that there is a degree of chemical interaction between the added ions and gold.

A transferência de carga entre adsorbatos moleculares doadores e nanopartículas (NPs) semicondutoras aceitadoras têm encontrado extensivas aplicações recentes em células fotovoltaicas e de combustíveis, em fotocatálise e em eletrônica molecular. Além disso, NPs têm sido usadas como suporte para reagentes moleculares, fotosintetizadores e fármacos para variados fins. A eficiência destes dispositivos moleculares depende do estudo detalhado da dinâmica de transferência de carga na interface entre uma NP e moléculas adsorvidas e, em particular, da transferência lateral de energia entre moléculas adsorvidas. Além disso, é necessário otimizar de um lado a atração Coulombiana entre doadores oxidados e aceitadores reduzidos e por outro lado as reações de ancoramento de modo que elas não fiquem limitadas ao encontro estocástico e difuso em solução. Em especial, tem-se observado uma crescente demanda por dispositivos fotovoltaicos híbridos construídos a partir de NPs de dióxido de titânio (TiO2). Estudos de estabilidade à longo prazo e modificações na interface de tais dispositivos são essenciais para se obter uma melhor eficiência. Também já é bem conhecida na literatura o uso de NPs de TiO2 como uma alternativa na degradação de corantes e tratamento de efluentes. Outra classe de estudos igualmente importante consiste na aplicação de porfirinas e seus derivados na geração de oxigênio singleto e no tratamento de câncer. Portanto, é de grande interesse o estudo de sistemas baseados nas propriedades das porfirinas e TiO2. O presente trabalho de mestrado teve como objetivo o estudo por técnicas espectroscópicas a) da adsorção de moléculas de porfirina emissora de luz na superfície de NPs semicondutoras de TiO2, b) dos processos ópticos envolvidos na transferência de carga e de energia na interface entre NP aceitadora e as porfirinas doadoras adsorvidas e do efeito da NP na fotoestabilidade e fotodegradação da porfirina. Em nosso estudo, escolhemos uma porfirina (Photogem® ou PG) como padrão de sistema molecular, pois apresenta bandas de absorção e emissão bem definidos. Foram utilizadas séries distintas de NPs de TiO2 com diferentes razões de área superficial por volume e porcentagens das fases predominantes rutilo e anatase preparadas sob diversas condições pelo método dos precursores poliméricos. Desenvolvemos um método que consiste na centrifugação das NPs juntamente com as moléculas adsorvidas e posterior analise óptica da solução sobrenadante para estudar a adsorção das porfirinas na superfície do TiO2. Observamos que NPs de TiO2 com predominância da fase anatase em sua estrutura possui maior interação e, consequentemente, maior adsorção molecular. A fase rutilo possui baixa adsorção molecular por ser extremamente estável. A afinidade e interação entre porfirina e partículas de TiO2 em solução foram analisadas para diferentes valores de pH. Também foram estudados efeitos da agregação e cobertura molecular nos processos de fotodegradação e de transferência lateral de energia entre moléculas adsorvidas. / Actually, charge transfer processes between molecular adsorbate donors and semiconductor nanoparticles (NPs) acceptors have found extensive applications in photocatalysis, photovoltaics cells and molecular electronics. Moreover, NPs have been used as carrier by molecular reagents, photosynthesizing and drugs for various purposes. The efficiency of these molecular devices depends on the detailed study of the dynamics of charge transfer at the interface between NPs and adsorbed molecules and, in particular, the lateral energy transfer between adsorbed molecules. Furthermore, it is necessary to optimize the Coulomb attraction between oxidized donors and reduced acceptors as well as anchoring reactions so that they are not limited by stochastic and diffuse interaction in solution. In particular, there has been a growing demand for hybrid photovoltaic devices based on nanoparticles of titanium dioxide (TiO2-NPs). Studies of long-term stability and interface modification are essential to obtain devices with better efficiency. Also well known in literature it is the employ of TiO2-NPs as an alternative in dye degradation and wastewater treatment. Another class of important study is based on the application of porphyrins and their derivatives in the generation of singlet oxygen and treatment of cancer. Thus, it is of great interest the study of systems based on porphyrin and TiO2 properties. The present work had as objective the study by spectroscopic technics: a) the adsorption of a light-emitting porphyrin on the TiO2-NPs surfaces, b) optical processes involved in charge and energy transfer in the interface between NP acceptor and porphyrins donors and the effect of NP on the photostability and photodegradation of porphyrins. In our study, we chose a porphyrin (or PG Photogem ®) as standard molecular system, because it shows well defined absorption and emission bands. We used TiO2-NPs which differ in area/volume ratios and in the percentage of rutile and anatase phases that predominates under different conditions of preparation by polymeric precursor method. We developed a method based on the centrifugation of the NPs with adsorbed molecules and subsequent optical analysis of the supernatant solution to study the adsorption of porphyrins on TiO2-NPs surfaces. We observed that TiO2-NPs with predominantly anatase phase in its structure has greater interaction and, consequently, higher molecular adsorption. The rutile phase has low molecular adsorption due to your great stability. The affinity and interaction between porphyrin and TiO2-NPs in solution were analyzed for different pH values. Other subjects discussed in this work include molecular aggregation effects and coverage during photodegradation and lateral energy transfer between adsorbed molecules.

by Yuk-Lin Chan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 78-83). / Abstracts in English and Chinese. / Abstract (English version) --- p.i / Abstract (Chinese version) --- p.ii / Acknowledgments --- p.iii / Table of Contents --- p.iv / List of Figures --- p.vi / List of Tables --- p.vii / Chapter 1. --- Introduction / Chapter 1.1 --- Indoor Air Pollution --- p.1 / Chapter 1.2 --- Typical Treatment of Air Pollutant --- p.6 / Chapter 1.3 --- Photocatalytic Degradation over Titanium Dioxide --- p.7 / Chapter 1.4 --- Advantages of Titanium Dioxide as a Photocatalyst --- p.12 / Chapter 1.5 --- Applications of Photocatalytic Degradation in Pollution Control --- p.14 / Chapter 1.5.1 --- Aqueous Phase Decontamination --- p.15 / Chapter 1.5.2 --- Gas Phase Decontamination --- p.15 / Chapter 1.6 --- Development of the Photocatalytic Degradation Technique --- p.16 / Chapter 1.6.1 --- Pure Ti02 --- p.17 / Chapter 1.6.2 --- Design of the Reactors --- p.18 / Chapter 1.6.3 --- Metal Ion Dopants --- p.21 / Chapter 1.6.4 --- Mixture with Supports --- p.21 / Chapter 1.7 --- Adsorbent-Supported Titanium Dioxide --- p.22 / Chapter 1.7.1 --- Use of Adsorbents other than Zeolites --- p.22 / Chapter 1.7.2 --- Use of Zeolites --- p.25 / Chapter 1.8 --- Molecular Sieves --- p.29 / Chapter 2. --- Experimental / Chapter 2.1 --- Block diagram of the Reaction Setup --- p.31 / Chapter 2.2 --- Fixed Volume Batch Reactor --- p.32 / Chapter 2.3 --- Reagents --- p.34 / Chapter 2.3.1 --- Degussa P25 Ti02 powder --- p.34 / Chapter 2.3.2 --- Aldrich Molecular Sieves (Organophilic) --- p.35 / Chapter 2.3.3 --- Other Adsorbents Used for Comparison --- p.35 / Chapter 2.4 --- Instrumental Analysis --- p.36 / Chapter 2.4.1 --- Photoacoustic Multi-gas Monitor --- p.36 / Chapter 2.4.2 --- X-Ray Diffraction Analysis --- p.42 / Chapter 2.4.3 --- Scanning Electron Microscopy --- p.42 / Chapter 2.4.4 --- UV-vis Diffuse Reflectance Spectroscopy --- p.42 / Chapter 2.4.5 --- Iso-electron Point Measurements --- p.43 / Chapter 2.5 --- Photocatalytic Degradation of Simple Alkanes by P25 Titanium Dioxide --- p.45 / Chapter 2.6 --- Photocatalytic Degradation of Gaseous Acetone over Organophilic Molecular Sieves-Supported Titanium Dioxide --- p.49 / Chapter 3. --- Results and Discussion / Chapter 3.1 --- Photocatalytic Degradation of Simple Alkanes by P25 Titanium Dioxide --- p.52 / Chapter 3.1.1 --- Rate of Photocatalytic Degradation of Simple Alkanes --- p.52 / Chapter 3.1.2 --- Summary of Rate of Photocatalytic Degradation of Simple Alkanes --- p.57 / Chapter 3.2 --- Photocatalytic Degradation of Gaseous Acetone over Organophilic Molecular Sieves-Supported Titanium Dioxide --- p.58 / Chapter 3.2.1 --- The Adsorption Ability of Various Adsorbents --- p.58 / Chapter 3.2.2 --- XRD Pattern Measurement --- p.60 / Chapter 3.2.3 --- Scanning Electron Microscopy --- p.64 / Chapter 3.2.4 --- UV-vis Diffuse Reflectance Spectroscopy --- p.65 / Chapter 3.2.5 --- Iso-electron Point Measurements --- p.67 / Chapter 3.2.6 --- Photocatalytic Activity of Various Catalysts --- p.69 / Chapter 4. --- Conclusion --- p.76 / Bibliography --- p.78 / Appendix / "A Demonstration of Photocatalytic Degradation by Gaseous Organic Pollutant, Dichloromethane " --- p.83

Wu Xiujuan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 88-93). / Abstracts in English and Chinese. / ABSTRACT (Chinese) / ABSTRACT / ACKNOWLEDGEMENT / TABLE OF CONTENTS / LIST OF TABLES / LIST OF FIGURES / Chapter CHAPTER ONE: --- INTRODUCTION / Chapter 1.1 --- General B ackground --- p.1 / Chapter 1.2 --- Chromium in Environment and its Analysis --- p.2 / Chapter 1.2.1 --- Source of Chromium and its Harmful Effects on Human --- p.2 / Chapter 1.2.2 --- Methods for Separation and Determination of Chromium Species --- p.4 / Chapter 1.3 --- Arsenic in the Environment and its Toxicity --- p.4 / Chapter 1.4 --- Properties of TiO2 and Its Applications --- p.6 / Chapter 1.4.1 --- Photocatalytic Property of TiO2 --- p.6 / Chapter 1.4.2 --- Surface Acid-Basic Property of TiO2 --- p.8 / Chapter 1.5 --- Adsorption --- p.11 / Chapter 1.6 --- Fundamental of ICP-AES and ICP-MS --- p.12 / Chapter 1.6.l --- Principle of ICP-AES --- p.12 / Chapter 1.6.2 --- Principle of ICP-MS --- p.14 / Chapter 1.7 --- Scope of Work --- p.18 / Chapter CHAPTER TWO: --- SEPERATION OF CHROMIUM SPECIES ON TIO2 / Chapter 2.1 --- Introduction --- p.19 / Chapter 2.2 --- Experimental --- p.23 / Chapter 2.2.1 --- Materials --- p.23 / Chapter 2.2.2 --- Instruments --- p.24 / Chapter 2.2.2.1 --- Coupling of TiO2 column and ICP-AES --- p.24 / Chapter 2.2.2.2 --- Coupling of TiO2 column and ICP-MS --- p.26 / Chapter 2.2.3. --- Procedure --- p.29 / Chapter 2.3 --- Results and Discussion --- p.33 / Chapter 2.3.1 --- Preliminary study on the adsorption of Cr(III) and Cr(VI) on TiO2 --- p.33 / Chapter 2.3.2 --- Development and Verification of the proposed method for speciation of Cr(III) and Cr(VI) in aqueous solution --- p.42 / Chapter 2.3.3 --- Practical application of the proposed method for separation and determination of Cr(III) and Cr(VI) --- p.46 / Chapter CHAPTER THREE: --- ADSORPTION OF ARSENIC SPECIES ON TiO2 / Chapter 3.1 --- Introduction --- p.61 / Chapter 3.2 --- Experimental --- p.66 / Chapter 3.2.1 --- Materials --- p.66 / Chapter 3.2.2 --- Instruments --- p.69 / Chapter 3.2.3 --- Procedure --- p.70 / Chapter 3.3 --- Results and Discussion --- p.71 / Chapter 3.3.1 --- Adsorption Kinetics --- p.71 / Chapter 3.3.2 --- Effect of pH on Adsorption of Arsenic Species --- p.71 / Chapter 3.3.3 --- Adsorption Isotherm --- p.74 / Chapter 3.3.4 --- Adsorption Model --- p.76 / Chapter 3.3.5 --- Factors Affecting the Adsorption of Arsenic Species on p25 and Rutile TiO2 --- p.83 / Chapter CHAPTER FOUR: --- CONCLUSION --- p.86 / REFERENCES --- p.88

"The simultaneous degradation of five organic contaminants: 1,4 dioxane, n-nitrosodimethylamine, tris-2-chloroethyl phosphate, gemfibrozil, and 17β estradiol, was investigated using a 1 L batch water-jacketed UV photoreactor utilizing titanium dioxide (TiO2) nanoparticles (Degussa P-25) as a photocatalyst. The primary objectives of this research were: (1) to experimentally assess the feasibility of heterogeneous photocatalysis as a promising alternative for the degradation of organic compounds in water; and (2) to model the chemical reactions by the application of two different approaches based on adsorption – surface reactions (Langmuir–Hinshelwood) and its simplification to a first order rate reaction. These objectives were motivated by the lack of information regarding simultaneous degradation of organic compounds in different categories as found in real aqueous matrices, and generation of specific intermediates that could eventually represent a potential risk to the environment. Contaminants were chosen based on their occurrence in water sources, their representativeness of individual sub-categories, and their importance as part of the CCL3 as potential contaminants to be regulated. Contaminant degradation was evaluated over time, and the TiO2 concentration and solution pH were varied under constant UV irradiation, oxygen delivery rate, mixing gradient, and temperature. 

 Specific accomplishments of this study were: (1) reaction kinetics data were obtained from the UV/TiO2 experiments and showed the potential that this UV/TiO2 process has for effectively removing different types of organic compounds from water; (2) a good fit was obtained between photocatalytic reaction kinetics models and the contaminant data using pseudo first-order and Langmuir-Hinshelwood (L-H) models; (3) results of the analytical methods developed in this study were validated by measurements performed by a certified laboratory; (4) the reaction kinetic parameters obtained in this study were normalized to electrical energy per order, reactor volume and surface area of the photocatalyst in order to provide rate constants with wider applicability for scale-up to more complex systems; and (5) degradation intermediates from the oxidation process and from interaction among compounds were identified and possible pathways for their formation suggested. This research has provided a better understanding of the photocatalytic process for the removal of organic contaminants from complex aqueous matrices."

"The phase content and grain size of titanium dioxide often have a strong influence on properties for a variety of applications. In many cases it would be desirable to produce the stable rutile phase with an ultra-fine particle size (<10nm), but most low temperature synthesis methods produce predominantly the metastable anatase phase. The anatase-rutile transformation in TiO2 is known to be affected by dopant type and concentration, as well as the titanium precursor used in solution chemical synthesis. Recently, use of cavitation in the synthesis process has been shown to yield smaller grain size for a variety of oxides. However, the relative importance of these synthesis variables on the grain size and phase content of TiO2 is not well understood. In this study, Taguchi analysis was used to determine the relative effects of dopants (Sn), titanium precursor (butoxide, sulfate, chloride), and cavitation power on grain size and phase content. Precursor residuals were also measured by analytical chemistry. Grain size and phase content results were analyzed statistically to determine whether there is a size dependence of the anatase-rutile transformation. Results show that grain size is strongly dependent on the concentration of chlorine. Absent chlorine, a definite grain size-phase content correlation exists; rutile content increases as grain size decreases. An L-4 orthogonal Taguchi analysis shows chlorine content and tin content as the major influences on the final product. With minimum grain size and maximum rutile content being considered optimal, our best result was 100% rutile and an average grain size of 5nm, which was achieved by acoustic synthesis with 3% tin dopant and low residual chlorine. "

This thesis focuses on the synthesis and characterisation of titanium dioxide (TiO2) thin films for photocatalytic applications and use in semi-transparent dye-sensitised solar cells for energy efficient glazing. Several synthetic methods for the production of TiO2 thin films are explored including sol-gel, aerosol-assisted chemical vapour deposition (CVD) and hybrid combinatorial CVD. For sol-gel processing two different precursors were studied; titanium tetra-isopropoxide (TTIP) and titanium bis-ammonium lactato dihydroxide (TiBALD). Non-ionic surfactants (Tween 20, 40, 60 and Brij 58 and 98) were successfully incorporated into all three methods for the production of TiO2 thin films modified morphology, microstructure and enhanced functional properties in some cases. All films are fully characterised using scanning electron microscopy, X-ray diffraction, atomic force microscopy, Raman spectroscopy, UV-Vis spectroscopy, contact angle analysis, as well as assessment for photocatalytic performance with resazurin 'intelligent' ink. Photocatalytic performance has been used as an indicator for performance in dye-sensitised solar cells (DSSCs). The best photocatalytic performances with half-lives of up to 2 minutes were obtained for thin films produced with the addition of Brij surfactants. A selection of thin films were tested in semi-transparent DSSC devices with up to 70% transparency, to determine their overall potential for use as energy-efficient glazing. Three DSSC device configurations were tested, whereby the optimum configuration used N3 "black" dye with a dye loading time of 42 hours in combination with a high performance iodine electrolyte and a platinum counter electrode. The highest power conversion efficiencies (PCE) obtained were within the region of 0.1 - 0.3 %, with the highest PCE of 0.3814 % obtained with a 3-layer TTIP sol-gel derived Brij 58 thin film (0.0006 mol dm3) which exhibited an short-circuit current of 0.857 mA/cm2, an open-circuit voltage of 0.71 V and a fill factor of 0.60.

Orientador: Paulo Noronha Lisboa Filho / Banca: Francisco Trivinho Strixino / Banca: José Humberto Dias da Silva / Resumo: Considerando a crescente demanda por energia elétrica e as mudanças ambientais causadas pela utilização de fontes energéticas não renováveis, a energia solar apresenta-se como uma boa alternativa aos combustíveis fósseis. Dentre os dispositivos fotovoltaicos, as células solares sensibilizadas (DSSC's) utilizam materiais abundantes na natureza e de baixo custo. No entando, é necessário um aperfeiçoamento das mesmas para aumentar sua eficiência e torná-las comercializáveis. Para se obter uma boa eficiência no dispositivo, é também essencial um controle das propriedades estruturais e ópticas dos semicondutores empregados. Nestes dispositivos, o dióxidode titânio é utlizado como semicondutor nas DSSC's por possuir um band gap larg que absorve luz em comprimentos de onda capazes de gerar pares elétron-buraco. Já o óxido de zinco é empregado como óxido semicondutor transparente por apresentar alto grau de transmitância optica. Filmes finos de TiO2 e ZnO foram sintetizados pela técnica sol-gel e depositadas por spin-coating em substratos de vidro com a finalidade de estudar as condições de deposição e investigar suas propriedades estruturais e ópticas. Os espécimes preparados foram caracterizados por difração de raios X, microscopia eletrônica de varredura, microscopia óptica confocal, microscopia de força atômica e espectroscopia na região do UV-Vis. As análises estruturais mostraram que a concentração de surfactante, os parâmetros de deposição dos filmes e as temperaturas de tratamento térmico empregadas têm grande influência sobre algumas propriedades dos filmes, sedo estas a aderência dos filmes no substrato vítreo, a fase cristalina formada, o tamanho de partícula e a uniformidade superficial dos filmes. Os estudos ópticos dos filmes de ZnO apresentaram um valor de band gap em acordo com os da literatura (3,3 e V) transmitância acima de 80%. Já os filmes de TiO2 apresentaram absorção em... / Abstract: Considering the rising demand for electricity and the environmental changes caused by the use of non-renewable energy sources, solar energy is presented as a good alternative to fossil fuels. Among the photovoltaic devides, dye sensitized solar cells (DSSC'S) use abundant in nature and low cost materials. Nevertheless, is necessary to improve the DSSC's by increasing their efficiency and making them marketable. To obtain a good efficiency in the device, it is also essential to control the structural and optical properties of the semiconductors employed. In these devices, the titanium dioxide is used as a semiconductor presenting a wide band-gap which absorbs light at wavelengths capable of genertaing electron-hole pairs. Zinc oxide is applied as a transparent conductor oxide which has high optical transmittance. Thin films of TiO2 and ZnO were synthesized by sol-gel route and deposited by spin-coating technique on glassy substrate in order to study the deposition conditions and investigate their structural and optical properties. The specimes were characterized by X-ray diffraction, scanning electron microscopy, confocal optical microscopy, atomic force microscopy and spectroscopyin the UV-Vis. Structural analysis showed that the surfactant concentration, the parameters of the film deposition and the heat treament temperatures employed had a major influence on the adhesion of the films at the glassy substrate, on the crystal phase formed, on the particle size and on the homegeneity of the film surface. The optical studies of ZnO showed a band gap value consistent with the literature (3.3 eV) and transmittance above 80%. TiO2 films exchibited absorption around 400 nm a high gap for the anatase crystalline phase of 4.1 eV, due to the presence of brookite phase. TiO2-ZnO films presented the same values for TiO2 films of 4.1 eV / Mestre

<div><p>The objective of this study was to investigate the effect of type and level of digestibility index marker (DIM) and dietary characteristics including dietary fiber type, dietary protein sources, and inclusion of xylanase in pigs and broiler chickens.</p><p> An experiment was conducted to investigate if (i) the apparent digestibility of gross energy (GE) and nitrogen (N) were influenced by the type of DIM and dietary fiber; (ii) the concentration pattern of DIM was influenced by dietary fiber, ileal digesta collection day (Day), and time period (TP). Eighteen barrows (initial BW = 24.2 ± 0.3 kg) fitted with a T-cannula at the end of the ileum were used in a 2-period study. Three corn-soybean meal-based diets were formulated with corn starch, corn bran or oat bran at 100 g/kg. Acid insoluble ash (AIA), chromic oxide (Cr₂O₃), and titanium dioxide (TiO₂) were included as DIM in each diet. Each period consisted of a 7-d adjustment period followed by a 3-d total fecal collection period and a 3-d ileal digesta collection period, where ileal digesta was collected every 3 h between 09:00 to 21:00 h with 4 TP on each of the 3 day. The DIM had similar effect on apparent ileal digestibility (AID) of GE and N within each diet, but different effects among the 3 diets. However, the apparent total tract digestibility (ATTD) of GE or N of corn starch and the ATTD of N of corn bran determined by the 3 DIM were not different. The recovery of TiO₂in feces of pigs fed the oat bran was 78.3%, which was the least among the 3 diets (<i>P</i>< 0.05). The distribution of Cr concentration in ileal digesta of pigs fed cornstarch, corn bran, and oat bran was similar to that of Tiand AIA irrespective of TP. In conclusion, the AID of GE or N was more influenced by the choice of DIM compared with ATTD; the recovery of TiO₂in pigs fed oat bran was less than corn starch or corn bran; the Day had limited effect on DIM concentration; and the three DIM moved synchronously in diets irrespective of TP.</p><p> Another study was conducted to investigate if the AID of GE or N was influenced by inclusion level and type of DIM and inclusion level of OB, and if the ATTD of GE or DIM recovery was influenced by the three aforementioned factors and duration of feces collection. Six diets were formulated as a 2 ´3 factorial arrangement with two levels of OB (0 or 100 g/kg) and three levels of DIM (2.5, 5.0, or 7.5 g/kg). BothCr₂O₃and TiO₂were added to the same diet as DIM and their inclusion levels were consistent in each experimental diet.<b></b>In Exp. 1, eighteen barrows (initial BW = 24.2 ± 0.3 kg) fitted with T-cannulas at the distal ileum were used in a triplicate 6 × 2 incomplete Latin Square design with 6 dietary treatments and 2 periods. The ileal digesta were collected for 3 d after 5-d adaptation. In Exp. 2, a total of 72 barrows (initial BW = 26.9 ± 0.5 kg) were used in a randomized complete block design, and the feces were collected for either 3 or 5 d after a 7-d adaptation according to the assignment. Experimental diets were same as Exp. 1. The AID of GE and N determined by TiO₂were greater (<i>P</i>< 0.05) than Cr₂O₃regardless of the OB level and DIM level. Neither the OB level nor the DIM level affected the AID of GE or N. The DIM level and duration of feces collection had no effect on ATTD of GE and DIM recovery. The ATTD of GE were greater (<i>P</i>< 0.05) determined by TiO₂than that determined by Cr₂O₃. Similarly, the recovery of TiO₂was greater (<i>P</i>= 0.007) than Cr₂O₃. Inclusion of 100 g/kg OB did not affect the recovery of DIM. In conclusion, the AID of GE and N, the ATTD of GE, and the recovery of Cr₂O₃or TiO₂were affected by DIM type, but not DIM level; the inclusion of OB had no effect on AID of GE and N, and DIM recovery; and the duration of feces collection had no effect on ATTD of GE, and DIM recovery.<b></b></p><p> The additivity of AID and standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AA) in mixed diets containing wheat, canola meal (CM), meat and bone meal (MBM), and sorghum distillers’ dried grains with solubles (DDGS) fed to pigs with Cr₂O₃and TiO₂as DIM was investigated in the third study. Four diets were prepared to contain wheat, CM, MBM, or DDGS as a sole source of N; three mixed diets were prepared to contain wheat, CM, and MBM; wheat, MBM, and DDGS; or wheat, CM, MBM, and DDGS; and a N-free diet was prepared to estimate the BEL of CP and AA. Both Cr₂O₃and TiO₂, each at 5 g/kg were incorporated into each diet. Sixteen barrows (initial BW = 34.7 ± 0.6 kg) surgically fitted with T-cannulas at the distal ileum were allotted to a duplicate 8 × 4 incomplete Latin square design with 8 experimental diets and 4 periods. Chromic oxide and TiO₂determined similar BEL, AID, and SID of CP and AA. In wheat-CM-MBM diet, the measured AID of CP and most AA determined with Cr₂O₃or TiO₂were not different from the predicted values. The results indicated that the determination of BEL, AID, and SID of CP and AA were not affected by DIM type;the additivity of AID and SID of CP and most indispensable AA in mixed diets was not affected by DIM type; and more accurate prediction of ileal digestibility of AA was achieved using SID rather than AID in mixed diets containing wheat, CM, MBM, and DDGS.</p><p> The aim of the last study was to investigate the growth performance and nutrient utilization responses of broiler chickens and the nutrient utilization of pigs to xylanase, experimental diet formulation method for energy (FME), and DIM. In Exp. 1, a total of 448 male broiler chickens were used in a randomized complete block design with BW as a blocking factor. Seven dietary treatments were prepared in a 3 × 2 + 1 factorial arrangement with inclusion of sand, diatomaceous earth (DAE), or wheat bran (WB) as FME and without or with xylanase (26,400 unit/kg of diet) plus positive control, which contained sufficient energy content for animals. Each of Cr₂O₃and TiO₂were incorporated at 5 g/kg in diets. In Exp. 2, twenty-one barrows (initial BW = 33.0 ± 0.3 kg), fitted with simple T-cannulas at the distal ileum, were used in a triplicate 7 × 2 incomplete Latin Square design with 7 dietary treatments, which were prepared by the same arrangement as in broilers. In Exp. 1, the growth performance of birds was not affected by xylanase, but was affected by the choice of FME. There were interactions (<i>P</i>< 0.05) between xylanase and FME for AID of CP, His, Met, Thr, and Trp. In Exp. 2, there were interactions (<i>P</i>< 0.05) between xylanase and FME for AID of dry matter, GE, Arg, and Lys. The DIM type had no effect on responses in pigs. In conclusion, the efficacy of xylanase on ileal energy and AA digestibility depends on the choice of FME in broilers and pigs, and DIM affects ileal digestibility in broilers.</p><p> In summary, the AID of GE or N was more influenced by the DIM type compared with ATTD, and the three DIM moved synchronously in diets irrespective of TP. The AID of GE and N, the ATTD of GE, and the recovery of Cr₂O₃or TiO₂were affected by DIM type, but not DIM level. However, the choice of DIM had no effect on the determination of BEL, AID, and SID of CP and AA, and additivity of AID and SID of CP and most indispensable AA in mixed diets. In addition, more accurate prediction of ileal digestibility of AA was achieved using SID rather than AID in mixed diets containing wheat, CM, MBM, and DDGS. Finally, the efficacy of xylanase on ileal energy and AA digestibility depends on the choice of FME in broilers and pigs, and DIM affects ileal digestibility in broilers.</p></div><p></p>