Download or read book Aspects of the Heterogeneous Photocatalytic Degradation of Organic Pollutants in Water written by Laurence Timothy Hogg and published by . This book was released on 1993 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: The photo-activity and specific surface area of a number of potentially-useful photocatalysts has been determined using the liquid phase dehydrogenation of propan-2-ol (activity), and the adsorption of argon gas at 77K (surface area). Degussa P25 titanium dioxide was considered the most active solid on this basis (activity=l23_+5xl0-4mol.g-1h-1, SA 39_+3 m2g-1). The photo-activity of suspended solids was found to be dependent upon the anatase:rutile ratio and the catalyst concentration, but relatively independent of the surface area for structurally different specimens. This has been explained in terms of the absorbance of band-gap radiation by the solid as a function of suspended particulate mass. Experimental evidence regarding the rate of propan-2-ol photo-oxidation under oxygen-purged conditions compared to the observed rate under air, suggests a rate dependence upon the partial pressure of oxygen of P02 1/2 The total photocatalytic mineralisation of aqueous 2-chlorophenol mediated by Degussa P25 TiO2 has been achieved in approximately 5 hours (c0 2CP = 5x10-4M), with an initial zero order rate constant of 1.7x10-4mol.g-1h-1. (6h irradiation period). The kinetics of the reaction are shown to be loosely expressed by the Langmuir-Hinshelwood kinetic model, but complex kinetics were in evidence under conditions of partial mineralisation, which may be dictated by the solution pH and/or the concentration of intermediate degradation products. A mechanism for the photo-oxidation reaction has also been proposed, based upon experimental evidence involving measurements of pH, conductance, carbon dioxide evolution and GCMS studies, which suggests a complex reaction pathway. The photocatalytic mineralisation of a saturated solution of gamma - hexachlorocyclohexane (Lindane, 7ppm), has been achieved in approximately 2 hours by this method and the mechanistic and kinetic details of this reaction are discussed briefly.

Download or read book Heterogeneous Photocatalysis written by M. Schiavello and published by . This book was released on 1997-10-09 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Heterogeneous Photocatalytic Degradation of Organic Pollutants in Water Over Nanoscale Powdered Titanium Dioxide written by Khaled M. Mezughi and published by . This book was released on 2011 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Photodegradation of Water Pollutants written by Martin M. Halmann and published by CRC Press. This book was released on 1995-12-05 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Photodegradation of Water Pollutants written by Martin M. Halmann and published by CRC Press. This book was released on 2024-11-01 with total page 319 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Heterogeneous Photocatalysis written by Mario J. Muñoz-Batista and published by Springer Nature. This book was released on 2020-07-01 with total page 301 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field. The chapter "Mechanochemical Forces as a Synthetic Tool for Zero and One-Dimensional Titanium Oxide-Based Nano-photocatalysts" is available open access under a CC BY 4.0 License via link.springer.com.

Download or read book Heterogeneous Photocatalytic Degradation Studies of Organic Compounds in Water written by Helen Chonde Ngwang and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Photocatalytic Reaction Engineering written by Hugo de Lasa and published by Springer Science & Business Media. This book was released on 2006-10-31 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heterogeneous photocatalysis is a novel technique for water purification. Publications on photocatalysis span a relatively recent period of not more than 25 years. This is a technique that, according to our extensive experience on the development of laboratory scale and pilot plant units, has great promise to eliminate water and air pollutants. Photocatalysis offers much more than competitive techniques where pollutants are transferred from phases; photocatalysis can achieve complete mineralization of pollutants leaving non-toxic species such as CO2 and H2O and can be exploited at close to room temperature and ambient pressure.

Download or read book Homogeneous and Heterogeneous Photocatalysis written by E. PELIZZETTI and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 720 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ever since the oil crisis of 1973, researchers in various fields of chemistry have proposed various schemes to conserve energy, as well to convert the sun's abundant and limitless supply of energy to produce chemical fuels (e. g. , hydrogen from water, . •. ). The enthusiasm had no previous parallel in the mid-1970's. Unfortunately, despite the several good proposals, the results have proven - in retrospect - somewhat disappointing from an economic viable point of view. The reasons for the meagre results are manyfold not the least of which are the experimental difficulties encountered in storage systems. Moreover, the lack of a concerted, well orchestrated interdisciplinary approach has been significant. By contrast, the chemical advances made in the understanding of the processes involved in such schemes have been phenomenal. A recent book on this issue ( M. Gratzel, Energy Resources through Photochemistry and Catalysis, 1983) is witness to the various efforts and approaches taken by researchers. In the recent years, many more groups have joined in these efforts, and the number of papers in the lit~rature is staggering ! One of the motives for organizing this NATO Advanced Research Workshop stemmed from our view that it was time to take stock of the accomplishments and rather than propose new schemes, it was time to consider seriously avenues that are most promising.

Download or read book Photocatalytic Degradation of Dyes written by Sushma Dave and published by Elsevier. This book was released on 2021-08-09 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Heterogeneous Photocatalytic Degradation of Organic Water Contaminants written by Craig Steven Turchi and published by . This book was released on 1990 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Water Pollution and Remediation Photocatalysis written by Inamuddin and published by Springer Nature. This book was released on 2020-10-29 with total page 443 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Heterogeneous Nanocomposite Photocatalysis for Water Purification written by Rajendra Pawar and published by William Andrew. This book was released on 2015-04-29 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Heterogeneous Nanocomposite-Photocatalysis for Water Purification, the authors introduce various heterogeneous photocatalysts based on novel nanostructures of metal oxide semiconductors and graphene used for water purification, including TiO2, Fe2O3, SnO2, WO3 and g-C3N4, and outlines their advantages and drawbacks. The nanocomposite-photocatalysts ZnO and CdS are compared with reduced graphene oxide (rGO), a rapidly growing materials system. The authors describe how the photocatalytic activity of known nanomaterials can be improved by modifying the structural and optical properties (i.e., phase composition). - Introductory portion of the book includes a brief survey of all different kinds of heterogeneous photocatalysts - Discusses the possible photocatalysis mechanism occurring during the degradation of different toxic pollutants - Provides the photoelectrochemical measurement for synthesized catalysts, supporting the effective transportation of photoelectrons resulting into better catalytic properties

Download or read book Photocatalysts for Organics Degradation written by Barbara Bonelli and published by MDPI. This book was released on 2020-06-23 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Photocatalysts in Advanced Oxidation Processes for Wastewater Treatment written by Elvis Fosso-Kankeu and published by John Wiley & Sons. This book was released on 2020-06-10 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photocatalysts in Advanced Oxidation Processes for Wastewater Treatment comprehensively covers a range of topics aiming to promote the implementation of photocatalysis at large scale through provision of facile and green methods for catalysts synthesis and elucidation of pollutants degradation mechanisms. This book is divided into two main parts namely “Synthesis of effective photocatalysts” (Part I) and “Mechanisms of the photocatalytic degradation of various pollutants” (Part II). The first part focuses on the exploration of various strategies to synthesize sustainable and effective photocatalysts. The second part of the book provides an insights into the photocatalytic degradation mechanisms and pathways under ultraviolet and visible light irradiation, as well as the challenges faced by this technology and its future prospects.

Download or read book Degradation of Organic Pollutants in Wastewater by Heterogeneous Photocatalysis written by Kanheya Mehrotra and published by . This book was released on 2002 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heterogeneous Photocatalysis written by Juan Carlos Colmenares and published by Springer. This book was released on 2015-12-24 with total page 419 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book explains the principles and fundamentals of photocatalysis and highlights the current developments and future potential of the green-chemistry-oriented applications of various inorganic, organic, and hybrid photocatalysts. The book consists of eleven chapters, including the principles and fundamentals of heterogeneous photocatalysis; the mechanisms and dynamics of surface photocatalysis; research on TiO2-based composites with unique nanostructures; the latest developments and advances in exploiting photocatalyst alternatives to TiO2; and photocatalytic materials for applications other than the traditional degradation of pollutants, such as carbon dioxide reduction, water oxidation, a complete spectrum of selective organic transformations and water splitting by photocatalytic reduction. In addition, heterogeneized polyoxometalate materials for photocatalytic purposes and the proper design of photocatalytic reactors and modeling of light are also discussed. This book appeals to a wide readership of the academic and industrial researchers and it can also be used in the classroom for undergraduate and graduate students focusing on heterogeneous photocatalysis, sustainable chemistry, energy conversion and storage, nanotechnology, chemical engineering, environmental protection, optoelectronics, sensors, and surface and interface science. Juan Carlos Colmenares is a Professor at the Institute of Physical Chemistry, Polish Academy of Sciences, Poland. Yi-Jun Xu is a Professor at the State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, China.