The Effect of Chemisorption on Heterogeneous Aqueous Photodegradation of Aromatic Compounds on Semiconducting Titanium Dioxide Particles, and Ceramic Membranes PDF Download
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Author: Simonetta Tunesi
Publisher:
ISBN:
Category :
Languages : en
Pages : 380
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Author: Simonetta Tunesi
Publisher:
ISBN:
Category :
Languages : en
Pages : 380
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Author:
Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 768
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Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 758
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Author: Maria K. Nowotny
Publisher: Trans Tech Publications Ltd
ISBN: 3038133736
Category : Technology & Engineering
Languages : en
Pages : 360
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Volume is indexed by Thomson Reuters BCI (WoS). The goal of this special volume was to provide a unique opportunity to exchange information, to present the latest results and to review relevant issues affecting contemporary diffusion research. The large number (over 232) of peer-reviewed papers emphasizes the considerable academic and industrial interest in this field.
Author: Khaled M. Mezughi
Publisher:
ISBN:
Category :
Languages : en
Pages : 212
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Organic contaminants from industrial and/or domestic effluents may be harmful to humans directly or indirectly by degrading the quality of the aquatic environment. Consequently these contaminants must be reduced to levels that are not harmful to humans and the environment before disposal. Chemical, physical and biological methods exist for the removal of these pollutants from effluents. Among the available chemical methods, heterogeneous photocatalytic oxidation has been found particularly effective in removing a large number of persistent organics in water. In this study, photocatalytic degradation was explored for the removal of reactive azo-dye (textile dye), triclocarban (disinfectant), clopyralid (herbicide) and three endocrine disrupting compounds (EDCs) (estrone, 17?-estradiol and 17?-ethinylestradiol) from synthetic effluents. The major factors affecting the photocatalytic processes including the initial concentration of the target compounds, the amount of catalyst, the light intensity, the type of catalyst, the electron acceptor, the irradiation time and the pH were studied. Other oxidation techniques including (O3, H2O2, UV) were also studied. Generally UV light is used in combination with titanium dioxide, as photocatalyst, to generate photoinduced charge separation leading to the creation of electron-hole pairs. The holes act as electron acceptors hence the oxidation of organics occur at these sites. These holes can also lead to the formation of hydroxyl radicals which are also effective oxidants capable of degrading the organics. The results obtained in this study indicated that photolysis (i.e. UV only) was found to have no effect on the degradation of reactive azo-dye (RO16). However, complete photocatalytic degradation of 20 mg/L (3.24?10-2 mM) RO16 was achieved in 20 minutes in the presence of 1g/L TiO2 Degussa P25 at pH 5.5. Comparison between various types of catalysts (i.e. Degussa P25, VP Aeroperl, Hombifine N) gave varied results but Degussa P25 was the most effective photocatalyst hence it was selected for this study. For RO16 the optimum catalyst concentration was 0.5 g/L TiO2 with initial concentration of 20 mg/L RO16. It was found that the disappearance of RO16 satisfactorily followed the pseudo first-order kinetics according to Langmuir-Hinshelwood (L-H) model. The rate constant was k= 0.0928 mol/min. Photodegradation of TCC was studied in 70%v acetonitrile: 30%v water solutions. UV light degraded TCC effectively and the reaction rates increased with decreasing initial concentration of TCC. UV/TiO2 gave unsatisfactory degradation of triclocarban (TCC) since only 36% were removed in 60 minutes with initial concentration of TCC 20 mg/L. The degradation of clopyralid and the EDCs was studied using three oxidation systems UV/TiO2, UV/H2O2 and O3. Complete degradation of clopyralid (3,6-DCP) was achieved with UV/TiO2 in about 90 minutes at an optimum catalyst concentration of 1g/L. Zero-order kinetics was found to describe the first stage of the photocatalytic reaction in the concentration range 0.078-0.521 mM. At pH 5 the rate constant was 2.09?10-6? 4.32?10-7 M.s-1.Complete degradation of all the three EDCs was achieved with UV/H2O2 in 60 minutes at catalyst concentration of (2.94?10-2 M). On the other hand complete degradation of the EDCs was achieved in just 2 minutes with ozonation. For high concentration EDCs, TiO2/UV gave low efficiency of degradation as compared with ozone and H2O2/UV. First-order kinetics was found to describe the photocatalytic reaction of the EDCs.
Author: Jerri Brown
Publisher: Nova Science Publishers
ISBN: 9781633213913
Category : Titanium dioxide
Languages : en
Pages : 0
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Engineered nanomaterials (ENMs) have greatly impacted human society as well as natural environments over the past decade, in consequence of their production on a massive scale to support the emerging market for nanotechnology. Among these ENMs, titanium dioxide (TiO2) nanoparticles have been extensively employed in the development of novel solutions for photocatalytic applications in environmental remediation. This book discusses the effects of TiO2 in natural environments. Some other topics discussed include indoor environment control with functional mortars; the production, properties and applications of TiO2; dye-sensitized TiO2 for gas detection; TiO2 induced photocatalytic reduction for organic synthesis; and the effects of TiO2 nanoparticles on the inflammatory process.
Author:
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ISBN:
Category :
Languages : en
Pages :
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Luminescence techniques are sensitive, selective, and widely used in analysis. Luminescence intensity is attenuated by quenchers. This research has focused on the use of surfactants such as CTAB, SDS, and TX-100 singly or together with TiO2 nanoparticles to evaluate their individual and combined effects on some fluorescent aromatic compounds such as pyrene, fluoranthene, anthracene, phenanthrene, and carbazole. Rutile phase TiO2 was synthesized using the low temperature sol-gel method. Carbazole and phenanthrene were severely quenched by all surfactants singly or in combination with TiO2. Anthracene and fluoranthene showed some enhancement in their luminescence intensity. The most dramatic effect was observed on the fluorescence intensity of pyrene. Pyrene showed enhanced fluorescence after degassing the solution alone or with the addition of the surfactants alone or in combination with TiO2 after degassing. These results showed that surfactants and TiO2 nanoparticles either singly or in combination should be useful for analysis employing luminescence techniques.
Author: Umar Ibrahim Gaya
Publisher: Springer Science & Business Media
ISBN: 9400777752
Category : Science
Languages : en
Pages : 222
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Book Description
This book underscores the essential principles of photocatalysis and provides an update on its scientific foundations, research advances, and current opinions, and interpretations. It consists of an introduction to the concepts that form the backbone of photocatalysis, from the principles of solid-state chemistry and physics to the role of reactive oxidizing species. Having recognised the organic link with chemical kinetics, part of the book describes kinetic concepts as they apply to photocatalysis. The dependence of rate on the reaction conditions and parameters is detailed, the retrospective and prospective aspects of the mechanism of photocatalysis are highlighted, and the adsorption models, photocatalytic rate expressions, and kinetic disguises are examined. This book also discusses the structure, property, and activity relationship of prototypical semiconductor photocatalysts and reviews how to extend their spectral absorption to the visible region to enable the effective use of visible solar spectrum. Lastly, it presents strategies for deriving substantially improved photoactivity from semiconductor materials to support the latest applications and potential trends.
Author: Innocent Udom
Publisher:
ISBN:
Category : Chemical engineering
Languages : en
Pages : 116
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This research investigated the supported semiconductor photocatalysts (TiO2 and ZnO), particularly ZnO nanorods and nanowires, their synthesis methods, properties and corresponding effectiveness in photocatalysis. The effect of transition metal co-catalysts on the photocatalytic properties of TiO2 was investigated. Although TiO2 is the most extensively studied photocatalyst for water decontamination, ZnO, as presented in this work, could be a substitute because of its lower cost, relative energy bandgap and higher visible light photoactivity. Both photocatalysts were doped and screened for the decomposition of model contaminates, rhodamine B (RhB), phenol and methyl orange, under ultraviolet and/or visible light irradiation. In the photodegradation of RhB, TiO2/Ru 1% showed a superior photocatalytic activity relative to P25-TiO2 under broad-band irradiation, while doped ZnO-Ag resulted in better photodegradation of methyl orange, compared to P25-TiO2, under visible light irradiation.
Author: Chih-Chang Wang
Publisher:
ISBN:
Category : Chlorophenols
Languages : en
Pages : 230
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