Development of a Novel TiO2-polymeric Photocatalyst for Water Purification Both Under UV and Solar Illuminations PDF Download
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Author: Debjani Mukherjee
Publisher:
ISBN:
Category :
Languages : en
Pages : 320
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Book Description
Comprising about 70% of the Earth's surface, water is undoubtedly the most precious natural resource. According to the W.H.O, around 3.5 million people are dying every year from different water related diseases. Different kinds of dyes and pharmaceutical products have been detected in drinking water, all over the world. These organic compounds being non removable by traditional water purification processes, made advanced oxidation processes come into existence. Among all kind of advanced oxidation processes, photocatalytic oxidation is the most promising one. The photocatalytic process is based on aqueous phase hydroxyl radical chemistry and couples low energy UV light with semiconductors acting as photocatalyst. The slurry form of TiO2 though being efficient has several disadvantages (particularly, post treatment expensive separation steps) which brings the immobilization of the catalysts on surfaces into existence. In this study, a TiO2-polymeric film photocatalyst was synthesized by reaction of gelatin, polyvinyl alcohol and polyvinyl pyrrolidone. TiO2 Degussa P25 powder was embedded into the polymeric matrix. The characterization of the film by OM, SEM, FTIR, revealed the topography of the catalyst films. Optimization of photocatalysts functionality was carried out by varying the cross linking methods and conducting several photodegradation reactions both under UV and solar light. Aspirin and methyl orange were chosen as model compounds, as traces of these compounds were detected in the drinking water of South-Western Ontario. The freeze-dried film photocatalyst was observed to degrade organic compounds efficiently, under both UV and solar illuminations. Degradation of high concentrated organic pollutants, was observed to follow Langmuir-Hinshelwood kinetics while at low concentration, first-order kinetics was observed. The effects of initial concentration, flow rate, pH, light intensity, photocatalyst loading, and thickness of the film on the degradation rates were studied. Mechanism of degradation of aspirin was studied from LC/MS analysis. The TOC analysis was carried out to analyse the organic carbon content of the intermediates formed during the course of degradation. Finally, photocatalytic degradation reaction was carried out in a continuous flow reactor under LED lights. film photocatalyst holds the potential of being an efficient and economical form of future photocatalyst for water purification.
Author: Debjani Mukherjee
Publisher:
ISBN:
Category :
Languages : en
Pages : 320
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Book Description
Comprising about 70% of the Earth's surface, water is undoubtedly the most precious natural resource. According to the W.H.O, around 3.5 million people are dying every year from different water related diseases. Different kinds of dyes and pharmaceutical products have been detected in drinking water, all over the world. These organic compounds being non removable by traditional water purification processes, made advanced oxidation processes come into existence. Among all kind of advanced oxidation processes, photocatalytic oxidation is the most promising one. The photocatalytic process is based on aqueous phase hydroxyl radical chemistry and couples low energy UV light with semiconductors acting as photocatalyst. The slurry form of TiO2 though being efficient has several disadvantages (particularly, post treatment expensive separation steps) which brings the immobilization of the catalysts on surfaces into existence. In this study, a TiO2-polymeric film photocatalyst was synthesized by reaction of gelatin, polyvinyl alcohol and polyvinyl pyrrolidone. TiO2 Degussa P25 powder was embedded into the polymeric matrix. The characterization of the film by OM, SEM, FTIR, revealed the topography of the catalyst films. Optimization of photocatalysts functionality was carried out by varying the cross linking methods and conducting several photodegradation reactions both under UV and solar light. Aspirin and methyl orange were chosen as model compounds, as traces of these compounds were detected in the drinking water of South-Western Ontario. The freeze-dried film photocatalyst was observed to degrade organic compounds efficiently, under both UV and solar illuminations. Degradation of high concentrated organic pollutants, was observed to follow Langmuir-Hinshelwood kinetics while at low concentration, first-order kinetics was observed. The effects of initial concentration, flow rate, pH, light intensity, photocatalyst loading, and thickness of the film on the degradation rates were studied. Mechanism of degradation of aspirin was studied from LC/MS analysis. The TOC analysis was carried out to analyse the organic carbon content of the intermediates formed during the course of degradation. Finally, photocatalytic degradation reaction was carried out in a continuous flow reactor under LED lights. film photocatalyst holds the potential of being an efficient and economical form of future photocatalyst for water purification.
Author: Fernando Pacheco-Torgal
Publisher: Woodhead Publishing
ISBN: 0081002092
Category : Technology & Engineering
Languages : en
Pages : 488
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Book Description
Since 1930 more than 100,000 new chemical compounds have been developed and insufficient information exists on the health assessment of 95 percent of these chemicals in which a relevant percentage are used in construction products. For instance Portland cement concrete, the most used material on the Planet (10.000 million tons/year that in the next 40 years will increase around 100 %) currently used in around 15% of total concrete production contains chemicals used to modify their properties, either in the fresh or hardened state. Biopolymers are materials that are developed from natural resources. They reduce dependence on fossil fuels and reduce carbon dioxide emissions. There is a worldwide demand to replace petroleum-based materials with renewable resources. Currently bio-admixtures represent just a small fraction of the chemical admixtures market (around 20%) but with environmental awareness for constituents in construction materials generally growing (the Construction Products Regulation is being enforced in Europe since 2013), the trend towards bio-admixtures is expected to continue. This book provides an updated state-of-the-art review on biopolymers and their influence and use as admixtures in the development of eco-efficient construction materials. - Provides essential knowledge for researchers and producers working on the development of biopolymer-modified construction materials - Discusses the various types of biopolymers currently available, their different production techniques, their use as bio-admixtures in concretes and mortars and applications in other areas of civil engineering such as soil stability, wood preservation, adhesives and coatings - All contributions are made from leading researchers, who have intensive involvement in the design and use of biopolymers in construction materials
Author: Pierre Pichat
Publisher: John Wiley & Sons
ISBN: 3527645411
Category : Technology & Engineering
Languages : en
Pages : 436
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Book Description
Water is one of the essential resources on our planet. Therefore, fresh water and the recycling of waste-water are very important topics in various areas. Energy-saving green technologies are a demand in this area of research. Photocatalysis comprises a class of reactions which use a catalyst activated by light. These reactions include the decomposition of organic compounds into environmental friendly water and carbon dioxide, leading to interesting properties of surfaces covered with a photocatalyst: they protect e.g. against incrustation of fouling matter, they are self-cleaning, antibacterial and viricidal. Therefore, they are attractive candidates for environmental applications such as water purification and waste-water treatment. This book introduces scientists and engineers to the fundamentals of photocatalysis and enlightens the potentials of photocatalysis to increase water quality. Also, strategies to improve the photocatalytic efficacy are pointed out: synthesis of better photocatalysts, combination of photocatalysis with other technologies, and the proper design of photocatalytic reactors. Implementation of applications and a chapter on design approaches for photocatalytic reactors round off the book. 'Photocatalysis and Water Purification' is part of the series on Materials for Sustainable Energy and Development edited by Prof. G.Q. Max Lu. The series covers advances in materials science and innovation for renewable energy, clean use of fossil energy, and greenhouse gas mitigation and associated environmental technologies.
Author: Xinchen Wang
Publisher: John Wiley & Sons
ISBN: 3527837981
Category : Technology & Engineering
Languages : en
Pages : 389
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Book Description
UV-Visible Photocatalysis for Clean Energy Production and Pollution Remediation Comprehensive resource detailing fundamentals of photocatalysis, clean energy production, and pollution treatment, as well as recent developments in each field UV-Visible Photocatalysis for Clean Energy Production and Pollution Remediation: Materials, Reaction Mechanisms, and Applications provides current developments in photocatalytic reactions for both inorganic and organic-based materials which operate under UV-visible light or sunlight irradiation, with a focus on the fundamentals and applications in clean energy production and pollution remediation. The text curates interesting and important research surrounding photocatalysis for hydrogen production, including the fundamentals and photocatalytic remediation of our better environments, which covers the reduction of CO2 and fixation of N2 with H2O under UV-visible light or sunlight irradiation. The first chapter of the book introduces these diverse subjects by including a brief history of the developments of photocatalysis research since around the 1960s. Specific sample topics covered in this book include: Visible-light active photocatalysts in pollutant degradation and conversion with simultaneous hydrogen production Application of S-scheme heterojunction photocatalyst and the role of the defects on the photocatalytic reactions on ZnO Strategies for promoting overall water splitting with particulate photocatalysts via single-step visible-light photoexcitation Polymeric carbon nitride-based materials in aqueous suspensions for water photo-splitting and photo-reforming of biomass aqueous solutions to generate H2 Visible light-responsive TiO2 thin film photocatalysts for the separate evolution of H2 and O2 from water For chemists, scientists, physicists, and engineers across a wide range of disciplines, UV-Visible Photocatalysis for Clean Energy Production and Pollution Remediation is an essential resource for understanding current developments in photocatalytic reactions on both inorganic and organic-based materials which operate under UV-visible light or sunlight irradiation.
Author: Miguel Pelaez
Publisher:
ISBN:
Category :
Languages : en
Pages : 203
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Book Description
The prevalent and increasing occurrence of cyanobacteria and their toxins, known as cyanotoxins, in drinking water sources have become a potential health risk to humans. Physical treatment methods in conventional drinking water treatment have the capacity to remove cyanotoxins but are limited to a merely physical separation, where further treatment is required. Cyanotoxins are susceptible to chemical oxidation and recently advanced oxidation technologies (AOTs) and nanotechnologies (AONs), such as titanium dioxide (TiO2) photocatalysis, have been proven an effective alternative technology to chemically transform cyanotoxins in water. However, conventional TiO2 is restricted to UV light photoactivation for the generation of highly reactive oxygen species (i.e., hydroxyl radicals) representing an economical and technological limitation for the use of renewable energy sources such as solar light, since UV radiation accounts only for 5% of the total solar spectrum compared to the visible spectrum (~45%). This dissertation explored the development of nanostructured nitrogen and fluorine co-doped TiO2 (NF-TiO2) that can be activated under visible and solar light for the photocatalytic degradation of cyanotoxins in water. This work aimed to develop highly efficient NF-TiO2 nanoparticles and films to evaluate the environmental fate of microcystins, the most widespread and highly persistent group of cyanotoxins found in surface waters, and cylindrospermopsin which has emerged as the most significant toxin in freshwater sources. Specific attention was given to 1) the fundamental aspects on the synthesis method that influenced the physicochemical properties of NF-TiO2, such as the incorporation of nitrogen and fluorine in the structure of TiO2 and the synergistic effects induced by both dopants, 2) the surface interaction between the cyanotoxins and NF-TiO2 in different water matrix, 3) the reactivity and degradation kinetics of microcystins and cylindrospermopsin with NF-TiO2 and 4) the mechanism of radical formation with NF-TiO2 under visible and solar light. The existence of interstitial nitrogen and substitutional fluorine in the NF-TiO2 lattice was determined and the formation of localized intra-gap states was established implying that fluorine promotes nitrogen incorporation in TiO2. A shift in the absorbance capacity of NF-TiO2 in the visible range was also observed. Anatase/brookite heterojunctions, which promote photocatalytic efficiency, were found in NF-TiO2. High initial degradation rates for microcystin-LR (MC-LR) were obtained with NF-TiO2 nanoparticles and films in synthetic water under visible light. The effect of pH indicated that attractive forces at acidic conditions between the oppositely charged NF-TiO2 and MC-LR contributed to higher MC-LR initial degradation rates. The presence of alkalinity and natural organic matter had a scavenging effect since the initial MC-LR degradation rates decreased. Modifications to NF-TiO2 with Evonik Aeroxide P25-TiO2 (P25) nanoparticles lead to composite NF-TiO2-P25 with improved photocatalytic activity towards MC-LR, MC-RR, MC-YR, MC-LA and cylindrospermopsin under visible and UV-vis light. The general reactivity was MC-LA>MC-LR>MC-YR>MC-RR. Finally, results using selected scavengers indicate that the main mechanism of NF-TiO2 radical formation under visible light irradiation differed from UV-mediated TiO2 photocatalysis since no evidence of hydroxyl radical production from the surface holes was observed. It was suggested that under visible light, surface oxygen reduction of NF-TiO2 occurred to form superoxide radical anion as main radical specie. The affinity of the scavenger with NF-TiO2 and MC-LR in terms of pH was established as an important parameter to determine the radicals formed in this study.
Author: Vedran Jovic
Publisher:
ISBN:
Category : Hydrogen as fuel
Languages : en
Pages : 239
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Book Description
Concerns about the future availability of fossil fuels for electricity generation and transportation, together with the negative environmental impacts of fossil fuel use in these applications, motivates the search for alternative renewable energy technologies. Efficient harnessing of solar energy to either directly generate electricity (using photovoltaic devices) or to generate energy carriers such as hydrogen (using photoelectrochemical or photocatalytic systems) is widely viewed as the best approach for achieving future energy supply security. The development of a sustainable Hydrogen Economy, in which H2 will replace fossil fuels for electricity generation and transportation, hinges on the discovery of simple, low cost and sustainable technologies for H2 manufacture, distribution and storage. This thesis research supports the growth of a sustainable H2 Economy, and is aimed at the development of efficient Au/TiO2 photocatalysts for solar H2 production from alcohol-water mixtures. The initial aim of this research project was to examine the effect of Au loading and TiO2 support composition on the activity of Au/TiO2 photocatalysts for H2 production from ethanol-water and methanol-water mixtures under UV excitation (365 nm, 6.5 mW cm-2). A series of Au/TiO2 photocatalysts (Au loadings = 0-10 wt.%) are prepared by the deposition-precipitation with urea method, using Degussa P25 TiO2 (85 wt.% anatase, 15 wt.% rutile) as the support phase. TEM analyses showed that all of the photocatalysts comprised supported Au nanoparticles (average size 4-5 nm) located at interfacial sites between TiO2 particles. UV/Vis, XRD, XPS and photoluminescence measurements confirmed that the supported Au was in metallic form. H2 production tests were carried out under liquid slurry conditions, with the photocatalysts suspended in ethanol/water mixtures or methanol/water mixtures of different composition (ranging from pure water to pure alcohol). In the ethanol-water system, the highest hydrogen production rates (~34 mmol g-1 h-1, quantum yield = 22 %) were achieved at an ethanol:water ratio of 80:20 and Au loadings of 0.5-1 wt.%. For the methanol:water system, the optimum Au loading was the same, but the best methanol:water stoichiometry was 50:50. The optimal H2 production rates in these systems correspond to ~14 L kgCatal -1 min-1, comparable to the requirements of a 1 kW PEM fuel cell (15 L of H2 min-1). Results confirm that Au nanoparticles serve as cathodic sites for H2 production during reaction (by accepting electrons photoexcited in TiO2), whilst the presence of alcohol is necessary for achieving high H2 production rates by acting as a sacrificial hole scavenger and proton source. The rates of H2 production were enhanced by 20-40 % under simultaneous UV and visible excitation (both of intensity comparable to that in sunlight), due to stimulation of the Au localised surface plasmon resonance (LSPR) at 560-580 nm. The exact mechanism for this enhancement is unclear, though could be due to localised heating effects at the photocatalyst surface. The high hydrogen production rates achieved in the Au/TiO2 system when P25 TiO2 was used as the support phase suggested a likely synergistic interaction between the three components phases (anatase, rutile and gold). To explore this synergy, and the extent to which it promoted H2 production, pure anatase and rutile fractions were isolated from P25 TiO2 by selective chemical dissolution and then functionalized with Au nanoparticles (3 wt.% loading). H2 production rates in ethanol-water mixtures (under UV and UV/visible light) for the Au/anatase and Au/rutile photocatalysts were substantially lower than those determined for an Au/P25 TiO2 photocatalyst at the same gold loading. EPR studies suggest that in P25 TiO2 electrons migrate from the conduction band of rutile to anatase lattice traps across interfacial surface sites. Electron transfer from interfacial sites to Au is strongly dependent on the location of the gold nanoparticles on the TiO2 support. Synergistic electron transfer between the TiO2 polymorphs and Au nanoparticles is responsible for the higher rates of H2 production realised in the Au/P25 TiO2 system. Three phase interfacial sites, involving anatase, rutile and gold nanoparticles, are identified as catalytic 'hot-spots' for H2 production from alcohol-water mixtures. TiO2 inverse opals comprise a face-centred cubic (fcc) array of air spheres in a TiO2 matrix. Due to their three dimensional periodic structure, with periods on the length scale of visible light, these materials possess photonic band gaps (PBGs) which can be used to control and manipulate the flow of light. In particular, the ability of TiO2 inverse opals to reduce the group velocity of light at the PBG edges and thus suppress spontaneous emission (i.e. electron-hole pair recombination) makes these materials attractive as photocatalysts. Here, six different TiO2 inverse opal photonic crystals with PBGs along the [111] direction at 300, 345, 407, 491, 563 and 692 nm were fabricated in the form of powders and thin films by the colloidal crystal template technique. Colloidal crystals (synthetic opals) composing monodisperse PMMA colloids arranged on a fcc lattice were used as sacrificial templates. The PMMA colloidal crystal templates and their TiO2 inverse opal replicas all displayed angle dependent structural colour, as is typical for photonic crystals. The optical properties of these materials were consistent with photonic band structure calculations by the planewave expansion method based on their geometric structure and composition. The photocatalytic properties of the TiO2 inverse opals were first evaluated through gas-phase ethanol decomposition experiments under UV excitation. Slow photon photocatalytic enhancement was observed for the TiO2 inverse opal with a PBG along the [111] direction at 345 nm, due to overlap between the red edge of the PBG and the TiO2 absorption edge at 388 nm. At the edges of the PBG, electromagnetic radiation travels with a strongly reduced group velocity, which in this particular case served to both enhance momentum transfer between incident photons and the semiconductor, as well as suppress electron-hole pair recombination in TiO2. Decoration of the TiO2 inverse opals with gold nanoparticles greatly enhanced their activity for photocatalytic H2 production from ethanol-water mixtures, by the same mechanism seen in the Au/P25 TiO2 system. Results guide the development of next generation semiconductor photocatalysts for H2 production from biofuels.
Author: Vincenzo Augugliaro
Publisher: Royal Society of Chemistry
ISBN: 1847558704
Category : Science
Languages : en
Pages : 259
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Book Description
The book deals with the environmentally friendly cleaning materials functionalized with TiO2, a widely known semiconductor giving rise to redox reactions under artificial or solar irradiation. The role of titanium dioxide in the worldwide community is introduced first. The fundamental working principles of heterogeneous photocatalysis follow and a critical section on the semiconductor bulk and surface properties open the way to the differences between TiO2 blend features with respect to analogous thin film layouts. Then Follows the main section of the book which deals with the techniques applied to manufactured commercial devices, ranging from glasses to textiles and from concrete and other construction materials to paintings. Also road asphalt and other devices, such as photocatalytic air conditioning machines are outlined. Last generation materials, not yet commercialized, and the deposition techniques applied to prepare them are also widely discussed. The final part of the book covers the difficult and modern topic of standardization and comparison of performance of photocatalytic processes and in particular the guidelines proposed by various worldwide organizations for standardization are discussed. The book covers the general matters as well as the practical applications with the supporting methods discussed in detail. This book brings together a team of highly experienced and well-published experts in the field, providing a comprehensive view of the applications of supported titanium dioxide.
Author: Grigorios L. Kyriakopoulos
Publisher: Royal Society of Chemistry
ISBN: 1837670498
Category : Science
Languages : en
Pages : 375
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Book Description
Author: Elvis Fosso-Kankeu
Publisher: John Wiley & Sons
ISBN: 1119631440
Category : Science
Languages : en
Pages : 320
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Book Description
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.
Author: Vladimiro Dal Santo
Publisher: MDPI
ISBN: 3038976946
Category : Science
Languages : en
Pages : 208
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Book Description
Although the seminal work of Fujishima et al. dates back to 1971, TiO2 still remains the most diffused and studied semiconductor, employed in photo-oxidation processes for cleantech (i.e., polluted water and air treatment), in solar fuel production (mainly hydrogen production by water photo splitting), and in Carbon Capture and Utilization (CCU) processes by CO2 photoreduction. The eleven articles, among them three reviews, in this book cover recent results and research trends of various aspects of titanium dioxide photocatalysis, with the chief aim of improving the final efficiency of TiO2-based materials. Strategies include doping, metal co-catalyst deposition, and the realization of composites with plasmonic materials, other semiconductors, and graphene. Photocatalysts with high efficiency and selectivity can be also obtained by controlling the precise crystal shape (and homogeneous size) and the organization in superstructures from ultrathin films to hierarchical nanostructures. Finally, the theoretical modeling of TiO2 nanoparticles is discussed and highlighted. The range of topics addressed in this book will stimulate the reader’s interest as well as provide a valuable source of information for researchers in academia and industry.
