The Photocatalytic Degradation of Selected Phenolic Compounds and Biological Contaminations in the Vaal River in Mitigation of Fouling of Specific Polymer Membranes PDF Download
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Author:
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ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 0
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Book Description
Water quality from surface sources is fast deteriorating due to pollution from organic compounds. Among the organic compounds are chlorophenols, which are described as priority pollutants because of their detrimental effects. One way of removing them from water is by using membranes. However direct removal of chlorophenols using membranes is limited due to the inherent problem of membrane fouling. The thesis describes fabrication of thin film composite membranes modified with Ag-Ti02 and Ag-Zn0 for enhancing filtration properties of the membranes for removal of 2-CP and 2,4-DCP and improving the antifouling properties of the modified membranes.
Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 0
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Book Description
Water quality from surface sources is fast deteriorating due to pollution from organic compounds. Among the organic compounds are chlorophenols, which are described as priority pollutants because of their detrimental effects. One way of removing them from water is by using membranes. However direct removal of chlorophenols using membranes is limited due to the inherent problem of membrane fouling. The thesis describes fabrication of thin film composite membranes modified with Ag-Ti02 and Ag-Zn0 for enhancing filtration properties of the membranes for removal of 2-CP and 2,4-DCP and improving the antifouling properties of the modified membranes.
Author: Jesus Moreira del Rio
Publisher:
ISBN:
Category :
Languages : en
Pages : 434
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Book Description
Abstract Scaling up a photoreactor requires both knowledge of optical properties of the slurry medium and an established kinetic model. Measuring the scattering and absorption coefficients of particles suspended in water involves the use of specialized optical equipment, as well as the partial solution of the radiative transfer equation (RTE). In addition, modeling of the radiation field in photoreactors with complicated geometries offers special challenges. On the other hand, most of the kinetic models (KM) for phenol photodegradation reported in the literature were obtained for a single organic chemical species only. In fact, neglecting all the intermediate species generated during the photoreaction, is a common oversimplification that limits the KM application. As a result, once the radiation and kinetic models fully established, energy efficiencies can be obtained. In this PhD dissertation, the photocatalytic degradation of phenol over four different TiO2 catalysts is studied. It is proven that phenol yields hydroquinone, catechol, benzoquinone, and acetic and formic acids as main intermediate species. The radiation field inside photocatalytic reactors is predicted by solving the RTE. From the solution of the RTE, the local volumetric rate of energy absorption (LVREA) is also calculated. The radiation field inside an annular photoreactor is simulated using the Monte Carlo (MC) method for different TiO2 suspensions in water. All simulations are performed by using both the spectral distribution, and the wavelength-averaged scattering and absorption coefficients. The Henyey-Greenstein phase function is adopted to represent forward, isotropic and backward scattering modes. It is assumed that the UV lamp reflects the back-scattered photons by the slurried medium. It is proven, photo-absorption rates, using MC simulations and spectral distribution of the optical coefficients, agree closely with experimental observations from a macroscopic balance (MB). It is also found that the scattering mode of the probability density function, is not a critical factor for a consistent representation of the radiation field. iv When solving the RTE, two optical parameters are needed: (1) the absorption and scattering coefficients, and (2) the phase function. In this research work, the MC method, along with an optimization technique, is shown to be effective in predicting the wavelength-averaged absorption and scattering coefficients for different TiO2 powders. To accomplish this, the LVREA and the transmitted radiation (Pt) in the photoreactor are determined by using a MB. The optimized coefficients are calculated ensuring that they comply with a number of physical constrains, falling in between bounds established via independent criteria. The optimization technique is demonstrated by finding the absorption and scattering coefficients for different semiconductors that best fit the experimental values from the MB. The objective function in this optimization is given by the least-squared error for the LVREA. A photocatalyst is synthesized and its optical properties determined by the proposed method. This approach is a general and promising one; not being restricted to reactors of concentric geometry, specific semiconductors and/or particular photocatalytic reactor unit scale. Based on the proposed intermediate reactions, a phenomenological based unified kinetic model is proposed for describing the obtained experimental observations in phenol photodegradation. This Langmuir-Hinshelwood (L-H) kinetic model is based on a Series- Parallel reaction network. This reaction model is found to be applicable to the various TiO2 photocatalyst in the present study. This unified kinetic network is based on the identified and quantified chemical species in the photoconversion of phenol and its intermediates. In order to minimize the number of optimized parameters, the adsorption constants of the different intermediate species on the different catalysts configuration, are obtained experimentally. It is shown that the unified kinetic model requires a number of significant assumptions to be effective; avoiding overparametization. As a result, the unified kinetic model is adapted for each specific TiO2 photocatalyst under study. These different models adequately describe the experimental results. It is shown that this approach results in good and objective parameter estimates in the L-H kinetic model, which is typically applied to photocatalytic reactors. Finally, two efficiency factors, the quantum yield and the photochemical and thermodynamic efficiency factor, are obtained, in this PhD dissertation. These factors are based on the kinetic model proposed and the radiation being absorbed by the photocatalyst particles. The v efficiency calculations consider stoichiometric relationships involving observable chemical species and OH- groups. The obtained efficiency factors point toward a high degree of photon utilization and, as a result, the value of photocatalysis and Photo-CREC-Water reactors for the conversion of organic pollutants in water is confirmed.
Author: Marcos Soto-Hernández
Publisher: BoD – Books on Demand
ISBN: 9535129570
Category : Science
Languages : en
Pages : 458
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Book Description
Phenolic compounds as a large class of metabolites found in plants have attracted attention since long time ago due to their properties and the hope that they will show beneficial health effects when taken as dietary supplements. This book presents the state of the art of some of the natural sources of phenolic compounds, for example, medicinal plants, grapes or blue maize, as well as the modern methods of extraction, quantification, and identification, and there is a special section discussing the treatment, removal, and degradation of phenols, an important issue in those phenols derived from the pharmaceutical or petrochemical industries.
Author: Ravindra Pratap Singh
Publisher:
ISBN: 9780750337670
Category : Biomedical materials
Languages : en
Pages : 0
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Book Description
This reference text brings together comprehensive reviews of the latest research in the field of bionanomaterials, with a focus on fundamentals and biomedical applications. Detailed coverage of the classification, properties and synthesis of bionanomaterials is provided to enhance readers' understanding. The book combines new ideas to uplift the advancement of bionanomaterials in biomedical research and provides a valuable reference for researchers and advanced students in the fields of biomaterials, bionanotechnology and bioengineering. The major applications covered include nanobiosensing, nanomedicine, diagnostics, therapeutics, tissue engineering and green bionanotechnology. The properties and applications of synthetic bionanomaterials and molecularly-imprinted polymer-based bionanomaterials are also included.
Author: Aracely Hernández-Ramírez
Publisher: Springer
ISBN: 3319109995
Category : Science
Languages : en
Pages : 298
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Book Description
This critical volume examines the different methods used for the synthesis of a great number of photocatalysts, including TiO2, ZnO and other modified semiconductors, as well as characterization techniques used for determining the optical, structural and morphological properties of the semiconducting materials. Additionally, the authors discuss photoelectrochemical methods for determining the light activity of the photocatalytic semiconductors by means of measurement of properties such as band gap energy, flat band potential and kinetics of hole and electron transfer. Photocatalytic Semiconductors: Synthesis, Characterization and Environmental Applications provide an overview of the semiconductor materials from first- to third-generation photocatalysts and their applications in wastewater treatment and water disinfection. The book further presents economic and toxicological aspects in the production and application of photocatalytic materials.
Author: Ponnadurai Ramasami
Publisher: Springer
ISBN: 9783030202859
Category : Science
Languages : en
Pages : 565
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Book Description
These proceedings gather carefully selected, peer-reviewed contributions from the International Conference on Pure and Applied Chemistry (ICPAC 2018). The event, the latest installment in a biennial conference series, was held in July 2018 in Mauritius. The respective chapters in this unique collection reflect a wide range of fundamental and applied research in the chemical sciences and various interdisciplinary subjects. In addition to reviews, they highlight cutting-edge advances.
Author: Philippe Quevauviller
Publisher: John Wiley & Sons
ISBN: 0470058730
Category : Science
Languages : en
Pages : 408
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Book Description
The issue of water quality monitoring is becoming a huge area as the EU requirements for cleaner water increase. On-line monitoring involves measuring a body of water constantly and in-situ as opposed to analysing samples in the lab. Currently filling the gap in the market, Wastewater Quality Monitoring: On-line Methods provides information on how to produce the best analyses of wastewater in order to meet the above mentioned requirements. This reference will prove invaluable to all local water companies, industrial companies producing wastewater, as well as environment agencies and researchers.
Author: Marcel Mulder
Publisher: Springer Science & Business Media
ISBN: 940091766X
Category : Science
Languages : en
Pages : 575
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Book Description
III . 2 Preparation of synthetic membranes 72 III . 3 Phase inversion membranes 75 III. 3. 1 Preparation by evaporation 76 III . 3. 2 Precipitation. from the vapour phase 76 III . 3. 3 Precipitation by controlled evaporation 76 Thermal precipitation 76 III . 3. 4 III . 3. 5 Immersion precipitation 77 Preparation techniques for immersion precipitation 77 III . 4 Flat membranes 77 III . 4. 1 78 III . 4. 2 Tubular membranes 81 III . 5 Preparation techniques for composite membranes 82 III. 5. 1 Interfacial polymerisation Dip-coating 83 III . 5. 2 III . 5. 3 Plasma polymerisation 86 III . 5. 4 Modification of homogeneous dense membranes 87 III . 6 Phase separation in polymer systems 89 III . 6. 1 Introduction 89 III . 6. 1. 1 Thermodynamics 89 III . 6. 2 Demixing processes 99 III . 6. 2. 1 Binary mixtures 99 III . 6. 2. 2 Ternary systems 102 III . 6. 3 Crystallisation 104 III . 6. 4 Gelation 106 III . 6. 5 Vitrification 108 III . 6. 6 Thermal precipitation 109 III . 6. 7 Immersion precipitation 110 III . 6. 8 Diffusional aspects 114 III . 6. 9 Mechanism of membrane formation 117 III. 7 Influence of various parameters on membrane morphology 123 III. 7. 1 Choice of solvent-nonsolvent system 123 III . 7. 2 Choice of the polymer 129 III . 7. 3 Polymer concentration 130 III . 7. 4 Composition of the coagulation bath 132 III . 7. 5 Composition of the casting solution 133 III . 7.
Author: Lawrence K. Wang
Publisher: CRC Press
ISBN: 9780203026519
Category : Science
Languages : en
Pages : 1368
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Book Description
Presenting effective, practicable strategies modeled from ultramodern technologies and framed by the critical insights of 78 field experts, this vastly expanded Second Edition offers 32 chapters of industry- and waste-specific analyses and treatment methods for industrial and hazardous waste materials-from explosive wastes to landfill leachate to w
Author: David M. Kempisty
Publisher: CRC Press
ISBN: 0429945027
Category : Science
Languages : en
Pages : 495
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Book Description
Per- and polyfluorinated alkyl substances (PFAS), often referred to as per- (and poly) fluorinated compounds (PFCs), have been used for years in many everyday3⁄4 and some lifesaving3⁄4 products. However, their use has been linked to adverse health effects in humans, a problem compounded by their persistence in the environment. This book discusses the various challenges of PFAS in our environment today, including their historical use as well as their chemical and toxicological properties. It also presents robust discussion of analytical challenges and special considerations in sampling. The work goes on to give practical recommendations for dealing with these compounds in today's dynamic regulatory landscape and includes several chapters on various remediation techniques. Key Features: Comprehensive overview of per- and polyfluorinated alkyl substances (PFAS) historical use and chemical/physical properties which help us understand their persistence, transport, and transformation pathways in the environment In-depth analysis of PFAS toxicology Detailed descriptions of conventional and state-of-the-art remediation technologies Practical recommendations for dealing with PFAS in a dynamic regulatory landscape Robust discussion of important sampling and analytical considerations Perfluoroalkyl Substances in the Environment: Theory, Practice, and Innovation explores the challenges across the topical areas of regulation and management, toxicology, environmental remediation, and analytical sampling and analysis.Readers will find this text helpful in understanding complexities associated with PFAS and informing management strategies to effectively protect this and future generations.
