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Author: Jimmy Lea
Publisher:
ISBN:
Category : Organic water pollutants
Languages : en
Pages : 282
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Book Description
Author: Jimmy Lea
Publisher:
ISBN:
Category : Organic water pollutants
Languages : en
Pages : 282
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Book Description
Author: Youn-Chul Oh
Publisher:
ISBN:
Category :
Languages : en
Pages : 346
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Book Description
This dissertation concerns the elucidation of degradation mechanisms of organic contaminants in aqueous suspension of TiO2, and extending understanding of photo catalysis condition to optimize degradation efficiency. The degradation mechanism of maleic acid, an important intermediate from the photocatalytic degradation of aromatic contaminants, was investigated via product distribution study and control experiments. The understanding of the mechanism of degradation of these compounds can assist us in ascertaining ideal conditions to perform the mineralization of recalcitrant organic compounds. The challenge to degrade a cyanyric acid, a recalcitrant species, by modifying TiO2 suspension was carried out. The addition of fluoride to aqueous suspensions of TiO2 has proved to be an important mechanistic tool in unraveling a long-standing conundrum in photocatalytic degradation. By using this method in parallel with other methods for producing homogeneous hydroxyl-type reagents, it is shown that cyanuric acid is susceptible to degradation under easily accessible conditions. There are isotope studies of photocatalysis of dimethyl phenyl phosphonate, a simple and safe form of organic phosphonate. Exposure of DMMP and related simple phosphonates to TiO2-mediated photocatalytic conditions results first in the loss of one of the methyl esters. An important unsettled mechanistic point is the mechanism by which the methyl is removed. Through the isotope studies of TiO2-mediated photocatalytic degradation of phosphonates, we can now understand removal of the alkyl ester portion of the compounds to produce phosphonic acid monoesters among the primary steps. The retention of 18O in the formation of MMPP clearly demonstrates that the dealkylation mechanism involves degradation of the methyl group exclusively, and neither attack at phosphorous by HO[Multiplied by][Subscript ads] or a related species, nor photoinduced hydrolysis. With an attempt to activate the modified TiO2 photo catalysts by the visible light and decrease the rapid recombination of excited electrons/holes during photoreaction, WO[Subscript x]-TiO2 powder was prepared by a sol-gel method. The WO[Subscript x]-TiO2 catalysts were characterized by XRD, XPS, and SEM-EDX. The degradation of 4-methoxyresorcinol by using WO[Subscript x]-TiO2 under visible light irradiation was observed.
Author: M. Schiavello
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 218
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Book Description
Photocatalysis is a reaction which is accelerated by light while a heterogeneous reaction consists of two phases ( a solid and a liquid for example). Heterogeneous Photocatalysis is a fast developing science which to date has not been fully detailed in a monograph. This title discusses the basic principles of heterogeneous photocatalysis and describes the bulk and surface properties of semiconductors. Applications of various types of photoreactions are described and the problems related to the modeling and design of photoreactors are covered.
Author: Barbara Bonelli
Publisher: MDPI
ISBN: 3039282867
Category : Science
Languages : en
Pages : 98
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Book Description
The quality of water is not only a technological and scientific issue, but a social and economic problem, in both developed and developing countries. Besides local regulations, which differ between regions and need constant upgrades, significant scientific developments are required in both the detection and removal of water contaminants. This Issue focuses on some recent advancements in the photocatalytic removal of organic pollutants, which is one of the aspects of the problem that involves the need of advanced catalysts and implies significant advancements in the field of materials science and chemical engineering.
Author: Inamuddin
Publisher: Springer Nature
ISBN: 303054723X
Category : Science
Languages : en
Pages : 443
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Book Description
In the context of climate change and fossil fuel pollution, solar energy appears as a cheap and sustainable fuel for many environmental applications, yet the efficiency of techniques has to be improved. This book reviews recent methods and applications of photocatalysis for the treatment of wastewater containing bacteria, heavy metals, organic pollutants, dyes and tannery effluents. Basics of water pollution, polluted river ecosystems and membranes are also detailed.
Author: Sushma Dave
Publisher: Elsevier
ISBN: 0128242027
Category : Technology & Engineering
Languages : en
Pages : 796
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Book Description
Photocatalytic Degradation of Dyes: Current Trends and Future Perspectives covers in detail current trends and future aspects on photocatalytic degradation of organic dyes using novel photocatalytic techniques such as metallic nanoparticles, heterogeneous and hybrid systems using visible light irradiation. It highlights the most recent scientific and technological achievements and importance of degradation of dyes in the textile effluent by simple environmental friendly approaches using eco-friendly catalysts. It is of assistance to everyone interested in bioremediation of effluents: professionals, consulting engineers, academicians, and research scholars as well. - Describes the basic photocatalytic techniques and their application in wastewater treatment - Covers the key reactive species accounting for the photodegradation of different dyes, providing helpful guidelines that could be applied to foster the development of efficient photodegradation systems - Includes Description of a wide variety of catalysts and their application in degradation of dyes in the effluent of variable matrices (such as textile effluent, pharmaceutical industry effluent, food industry effluent) - Presents the application of doped semiconductors in the degradation of dyes, hybrid systems and their importance in the dye degradation - Describes the biological synthesis of metallic nanostructures and their use in dye degradation using visible range of light irradiation - Discusses the mechanistic aspect of the dye degradation using photo catalysts
Author: Khaled M. Mezughi
Publisher:
ISBN:
Category :
Languages : en
Pages : 212
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Book Description
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: Martin M. Halmann
Publisher: CRC Press
ISBN: 9780849324598
Category : Technology & Engineering
Languages : en
Pages : 322
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Book Description
Photodegradation of Water Pollutants, the only complete survey available of current photocatalytic methods for treating water pollutants, covers all aspects of light-stimulated detoxification. Ideal for researchers and students, this new book explains methods for pollution treatment that have proven more effective than conventional biodegradation. Photodegradation of Water Pollutants examines advanced oxidation processes that have been successful in treating the chemical substances produced by industrial effluents and intensive agriculture. These oxidation processes include irradiation with ultraviolet or visible light, the use of homogenous sensitizers, such as dyes, and the use of heterogeneous photocatalysts, such as dispersed semiconductors. In addition, Photodegradation of Water Pollutants addresses the naturally occurring self-cleaning of some pollutants in sunlit surface waters, as well as several alternative non-photochemical approaches to water treatment. Available treatment options are discussed for the main groups of water pollutants, including toxic inorganic ions (cyanides, heavy metals), hydrocarbon derivatives (oil spills, surfactants, pulp and paper wastes), halocarbons, organo-N, organo-P, and organo-S compounds. The text also contains a unique section on the economics of advanced oxidation pollution treatments.
Author: Martin M. Halmann
Publisher: CRC Press
ISBN: 1040286240
Category : Technology & Engineering
Languages : en
Pages : 319
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Book Description
Photodegradation of Water Pollutants, the only complete survey available of current photocatalytic methods for treating water pollutants, covers all aspects of light-stimulated detoxification. Ideal for researchers and students, this new book explains methods for pollution treatment that have proven more effective than conventional biodegradation. Photodegradation of Water Pollutants examines advanced oxidation processes that have been successful in treating the chemical substances produced by industrial effluents and intensive agriculture. These oxidation processes include irradiation with ultraviolet or visible light, the use of homogenous sensitizers, such as dyes, and the use of heterogeneous photocatalysts, such as dispersed semiconductors. In addition, Photodegradation of Water Pollutants addresses the naturally occurring self-cleaning of some pollutants in sunlit surface waters, as well as several alternative non-photochemical approaches to water treatment. Available treatment options are discussed for the main groups of water pollutants, including toxic inorganic ions (cyanides, heavy metals), hydrocarbon derivatives (oil spills, surfactants, pulp and paper wastes), halocarbons, organo-N, organo-P, and organo-S compounds. The text also contains a unique section on the economics of advanced oxidation pollution treatments.
Author: Muhammad Umar
Publisher:
ISBN:
Category : Technology
Languages : en
Pages :
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Book Description
Photocatalytic Degradation of Organic Pollutants in Water.
