Download or read book Parametric Evaluation of an Innovative Ultra Violet PhotocatalyticOxidation UVPCO Air Cleaning Technology for Indoor Applications written by William J. Fisk and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An innovative Ultra-Violet Photocatalytic Oxidation (UVPCO) air cleaning technology employing a semitransparent catalyst coated on a semitransparent polymer substrate was evaluated to determine its effectiveness for treating mixtures of volatile organic compounds (VOCs) representative of indoor environments at low, indoor-relevant concentration levels. The experimental UVPCO contained four 30 by 30-cm honeycomb monoliths irradiated with nine UVA lamps arranged in three banks. A parametric evaluation of the effects of monolith thickness, air flow rate through the device, UV power, and reactant concentrations in inlet air was conducted for the purpose of suggesting design improvements. The UVPCO was challenged with three mixtures of VOCs. A synthetic office mixture contained 27 VOCs commonly measured in office buildings. A building product mixture was created by combining sources including painted wallboard, composite wood products, carpet systems, and vinyl flooring. The third mixture contained formaldehyde and acetaldehyde. Steady state concentrations were produced in a classroom laboratory or a 20-m{sup 3} chamber. Air was drawn through the UVPCO, and single-pass conversion efficiencies were measured from replicate samples collected upstream and downstream of the reactor. Thirteen experiments were conducted in total. In this UVPCO employing a semitransparent monolith design, an increase in monolith thickness is expected to result in general increases in both reaction efficiencies and absolute reaction rates for VOCs oxidized by photocatalysis. The thickness of individual monolith panels was varied between 1.2 and 5 cm (5 to 20 cm total thickness) in experiments with the office mixture. VOC reaction efficiencies and rates increased with monolith thickness. However, the analysis of the relationship was confounded by high reaction efficiencies in all configurations for a number of compounds. These reaction efficiencies approached or exceeded 90% for alcohols, glycol ethers, and other individual compounds including d-limonene, 1,2,4-trimethylbenzene, and decamethylcyclopentasiloxane. This result implies a reaction efficiency of about 30% per irradiated monolith face, which is in agreement with the maximum efficiency for the system predicted with a simulation model. In these and other experiments, the performance of the system for highly reactive VOCs appeared to be limited by mass transport of reactants to the catalyst surface rather than by photocatalytic activity. Increasing the air flow rate through the UVPCO device decreases the residence time of the air in the monoliths and improves mass transfer to the catalyst surface. The effect of gas velocity was examined in four pairs of experiments in which the air flow rate was varied from approximately 175 m{sup 3}/h to either 300 or 600 m{sup 3}/h. Increased gas velocity caused a decrease in reaction efficiency for nearly all reactive VOCs. For all of the more reactive VOCs, the decrease in performance was less, and often substantially less, than predicted based solely on residence time, again likely due to mass transfer limitations at the low flow rate. The results demonstrate that the UVPCO is capable of achieving high conversion efficiencies for reactive VOCs at air flow rates above the base experimental rate of 175 m{sup 3}/h. The effect of UV power was examined in a series of experiments with the building product mixture in which the number of lamps was varied between nine and three. For the most reactive VOCs in the mixture, the effects of UV power were surprisingly small. Thus, even with only one lamp in each section, there appears to be sufficient photocatalytic activity to decompose most of the mass of reactive VOCs that reach the catalyst surface. For some less reactive VOCs, the trend of decreasing efficiency with decreasing UV intensity was in general agreement with simulation model predictions.
Download or read book Evaluation of Ultra Violet Photocatalytic Oxidation for Indoor AirApplications written by D. P. Sullivan and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Acceptable indoor air quality in office buildings may be achieved with less energy by combining effective air cleaning systems for volatile organic compounds (VOCs) with particle filtration then by relying solely on ventilation. For such applications, ultraviolet photocatalytic oxidation (UVPCO) systems are being developed for VOC destruction. An experimental evaluation of a UVPCO system is reported. The evaluation was unique in that it employed complex mixtures of VOCs commonly found in office buildings at realistically low concentrations. VOC conversion efficiencies varied over a broad range, usually exceeded 20%, and were as high as {approx}80%. Conversion efficiency generally diminished with increased air flow rate. Significant amounts of formaldehyde and acetaldehyde were produced due to incomplete mineralization. The results indicate that formaldehyde and acetaldehyde production rates may need to be reduced before such UVPCO systems can be deployed safely in occupied buildings.
Download or read book Evaluation of Ultra Violet Photocatalytic Oxidation UVPCO ForIndoor Air Applications written by William J. Fisk and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Efficient removal of indoor generated airborne particles and volatile organic compounds (VOCs) in office buildings and other large buildings may allow for a reduction in outdoor air supply rates with concomitant energy savings while still maintaining acceptable indoor air quality in these buildings. Ultra-Violet Photocatalytic Oxidation (UVPCO) air cleaners have the potential to achieve the necessary reductions in indoor VOC concentrations at relatively low cost. In this study, laboratory experiments were conducted with a scaled, prototype UVPCO device designed for use in a duct system. The experimental UVPCO contained two 30 by 30-cm honeycomb monoliths coated with titanium dioxide and 3% by weight tungsten oxide. The monoliths were irradiated with 12 UVC lamps arranged in four banks. The UVPCO was challenged with four mixtures of VOCs typical of mixtures encountered in indoor air. A synthetic office mixture contained 27 VOCs commonly measured in office buildings. A cleaning product mixture contained three cleaning products with high market shares. A building product mixture was created by combining sources including painted wallboard, composite wood products, carpet systems, and vinyl flooring. A fourth mixture contained formaldehyde and acetaldehyde. Steady-state concentrations were produced in a classroom laboratory or a 20-m{sup 3} environmental chamber. Air was drawn through the UVPCO, and single pass conversion efficiencies were measured from replicate air samples collected upstream and downstream of the reactor section. Concentrations of the mixtures were manipulated, with concentrations of individual VOCs mostly maintained below 10 ppb. Device flow rates were varied between 165 and 580 m{sup 3}/h. Production of formaldehyde, acetaldehyde, acetone, formic acid, and acetic acid as reaction products was investigated. Conversion efficiency data were generated for 48 individual VOCs or groups of closely related compounds. Alcohols and glycol ethers were the most reactive chemical classes with conversion efficiencies often near or above 70% at the low flow rate and near 40% at the high flow rate. Ketones and terpene hydrocarbons were somewhat less reactive. The relative VOC conversion rates are generally favorable for treatment of indoor air since many contemporary products used in buildings employ oxygenated solvents. A commercial UVPCO device likely would be installed in the supply air stream of a building and operated to treat both outdoor and recirculated air. Assuming a recirculation rate comparable to three times the normal outdoor air supply rate, simple mass-balance modeling suggests that a device with similar characteristics to the study unit has sufficient conversion efficiencies for most VOCs to compensate for a 50% reduction in outdoor air supply without substantially impacting indoor VOC concentrations. Formaldehyde, acetaldehyde, acetone, formic acid, and acetic acid were produced in these experiments as reaction byproducts. No other significant byproducts were observed. A coupled steady-state mass balance model is presented and applied to VOC data from a study of a single office building. For the operating assumptions described above, the model estimated a three-fold increase in indoor formaldehyde and acetaldehyde concentrations. The outcome of this limited assessment suggests that evaluation of the potential effects of the operation of a UVPCO device on indoor concentrations of these contaminants is warranted. Other suggested studies include determining VOC conversion efficiencies in actual buildings and evaluating changes in VOC conversion efficiency as monoliths age with long-term operation.
Download or read book Experimental Evaluation of Indoor Air Cleaning Technologies and Modeling of UV PCO photocatalytic Oxidation Air Cleaners Under Multiple VOCs Conditions written by Wenhao Chen and published by . This book was released on 2007 with total page 267 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of this study were to: (1) develop much needed test methods and datasets for determining the performance of various air cleaning technologies, and (2) improve the understanding and develop a simulation model for the performance prediction of ultraviolet photocatalytic oxidation (UV-PCO) devices under multiple volatile organic compounds (VOCs) conditions.
Download or read book Experimental Evaluation and Modeling of Photocatalytic Oxidation Air Cleaners written by Lexuan Zhong and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaluation of a Combined Ultraviolet Photocatalytic Oxidation UVPCO written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We previously reported that gas-phase byproducts of incomplete oxidation were generated when a prototype ultraviolet photocatalytic oxidation (UVPCO) air cleaner was operated in the laboratory with indoor-relevant mixtures of VOCs at realistic concentrations. Under these conditions, there was net production of formaldehyde and acetaldehyde, two important indoor air toxicants. Here, we further explore the issue of byproduct generation. Using the same UVPCO air cleaner, we conducted experiments to identify common VOCs that lead to the production of formaldehyde and acetaldehyde and to quantify their production rates. We sought to reduce the production of formaldehyde and acetaldehyde to acceptable levels by employing different chemisorbent scrubbers downstream of the UVPCO device. Additionally, we made preliminary measurements to estimate the capacity and expected lifetime of the chemisorbent media. For most experiments, the system was operated at 680-780 m3/h (400-460 cfm). A set of experiments was conducted with common VOCs introduced into the UVPCO device individually and in mixture. Compound conversion efficiencies and the production of formaldehyde and acetaldehyde were determined by comparison of compound concentrations upstream and downstream of the reactor. There was general agreement between compound conversions efficiencies determined individually and in the mixture. This suggests that competition among compounds for active sites on the photocatalyst surface will not limit the performance of the UVPCO device when the total VOC concentration is low. A possible exception was the very volatile alcohols, for which there were some indications of competitive adsorption. The results also showed that formaldehyde was produced from many commonly encountered VOCs, while acetaldehyde was generated by specific VOCs, particularly ethanol. The implication is that formaldehyde concentrations are likely to increase when an effective UVPCO air cleaner is used in buildings containing typical VOC sources. The magnitude of the expected increase will depend upon a number of interrelated factors. Series of experiments were conducted to determine if the oxidizer, sodium permanganate (NaMnO4·H2O), has sufficient reaction rates and capacity to counteract formaldehyde and acetaldehyde production and enable a 50 % reduction in building ventilation rate without net increases in indoor aldehyde concentrations. A commercially produced filter element and two laboratory-fabricated media beds containing NaMnO4·H2O chemisorbent media were evaluated. The effectiveness of a device for removal of formaldehyde, acetaldehyde and other VOCs was determined by measurement of concentrations immediately upstream and downstream of the device. In some experiments, conversion efficiencies and byproduct generation by the UVPCO device also were determined. Six experiments were conducted with the commercial filter element installed downstream of the UVPCO reactor. Eleven experiments were conducted with a single panel media bed (30 cm by 61 cm by 2.5 cm deep) installed downstream of the UVPCO reactor; in these, the effects of temperature and air residence time on conversion efficiency were examined. Two experiments were conducted with a four-panel, folded, media bed (approximately four times the size of the single panel bed) installed downstream of the reactor. Because the commercial unit contained activated carbon as an additional component, it was effective at removing lower volatility compounds that typically have low oxidation rates in the UVPCO reactor. The filter element also met the minimum efficiency objective for formaldehyde. However, the removal of acetaldehyde was less than required. The air residence time in the single panel bed was not optimized as the removal efficiencies for both formaldehyde and acetaldehyde were strongly inversely related to the air flow rate through the device. In addition, the acetaldehyde removal efficiency decreased to less than 10% with extended use of the device. The folded bed was considerably more effective; formaldehyde was removed with greater than 90% efficiency, and acetaldehyde was removed at about 70% efficiency. With the combined UVPCO/chemisorbent system, the net removal efficiencies for formaldehyde and acetaldehyde were 90% and 40%, respectively. In summary, the use of a multi-panel, folded scrubber filled with NaMnO4·H2O chemisorbent media downstream of the prototype UVPCO air cleaner effectively counteracted the generation of formaldehyde and acetaldehyde due to incomplete oxidation of VOCs in the UVPCO reactor. Thus, this combined UVPCO air cleaner and chemisorbent system appears to have sufficient VOC removal efficiency to enable a 50 % reduction in ventilation rate without increasing indoor aldehyde concentrations.
Download or read book Applying Nanotechnology for Environmental Sustainability written by Joo, Sung Hee and published by IGI Global. This book was released on 2016-08-04 with total page 585 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanomaterials have been used for years in industries such as consumer products, textile production, and biomedicine, yet the literature outlining their use in environmental causes is limited. The safety, toxicity, transportation, and removal of this technology must be addressed as nanotechnology and nanomaterial use is expected to grow. Applying Nanotechnology for Environmental Sustainability addresses the applications of nanomaterials in the field of environmental conservation and sustainability, and analyses the potential risks associated with their use. It elucidates the scientific concepts and emerging technologies in nanoscience and nanotoxicity by offering a wide range of innovative topics and reviews regarding its use. This publication is essential for environmental engineers, researchers, consultants, students, regulators, and professionals in the field of nanotechnology.
Download or read book Microbial Safety of Fresh Produce written by Xuetong Fan and published by John Wiley & Sons. This book was released on 2009-10-06 with total page 463 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microbial Safety of Fresh Produce covers all aspects of produce safety including pathogen ecology, agro-management, pre-harvest and post-harvest interventions, and adverse economic impacts of outbreaks. This most recent edition to the IFT Press book series examines the current state of the problems associated with fresh produce by reviewing the recent, high-profile outbreaks associated with fresh-produce, including the possible internalization of pathogens by plant tissues, and understanding how human pathogens survive and multiply in water, soils, and fresh fruits and vegetables.
Download or read book Fruit Preservation written by Amauri Rosenthal and published by Springer. This book was released on 2018-11-05 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fruits and fruit based products are, in most cases, associated with very good sensory characteristics, health, well-being, perishability, relatively easy to mix with food products of diverse origin, amenable to be processed by conventional and novel technologies. Given the multiplicity of aspects whenever fruit preservation is considered, the editors took the challenge of covering in a thorough, comprehensive manner most aspects dealing with this topic. To accomplish these goals, the editors invited well known colleagues with expertise in specific disciplines associated with fruit preservation to contribute chapters to this book. Eighteen chapters were assembled in a sequence that would facilitate, like building blocks, to have at the same time, a birds-eye view and an in-depth coverage of traditional and novel technologies to preserve fruits. Even though processing took center stage in this book, ample space was dedicated to other relevant and timely topics on fruit preservation such as safety, consumer perception, sensory and health aspects. FEATURES: Traditional and Novel Technologies to Process Fruits Microwaves Ohmic Heating UV-C light Irradiation High Pressure Pulsed Electric Fields Ultrasound Vacuum Impregnation Membranes Ozone Hurdle Technology Topics Associated with Fruit Preservation Safety Nutrition and Health Consumer Perception Sensory Minimal Processing Packaging Unit Operations for Fruit Processing Cooling and Freezing Dehydration Frying
Download or read book Postharvest Decay written by Silvia Bautista-Baños and published by Elsevier. This book was released on 2014-05-14 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by a diverse group of research professionals, Postharvest Decay: Control Strategies is aimed at a wide audience, including researchers involved in the study of postharvest handling of agricultural commodities, and undergraduate and graduate students researching postharvest topics. Growers, managers, and operators working at packinghouses and storage, retail, and wholesale facilities can also benefit from this book. The information in this book covers a wide range of topics related to selected fungi, such as taxonomy, infection processes, economic importance, causes of infection, the influence of pre-harvest agronomic practices and the environment, the effect of handling operations, and the strategic controls for each host-pathogen, including traditional and non-traditional alternatives. - Includes eleven postharvest fungi causing serious rots in numerous fruits and vegetables - Offers selected microorganisms including pathogens of commercially important tropical, subtropical and temperate crops worldwide, such as tomatoes, pears, apples, peaches, citrus, banana, papaya, and mango, among others - Presents content developed by recognized and experienced high-level scientists, working in the postharvest pathology area worldwide - Provides basic information about each fungus, pre- and postharvest factors that contribute to infection and control measurements, including the use of chemicals and non-traditional methods
Download or read book Fungal Pigments written by Laurent Dufossé and published by MDPI. This book was released on 2018-03-23 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Fungal Pigments" that was published in JoF
Download or read book Nanomaterials for Environmental Protection written by Boris I. Kharisov and published by John Wiley & Sons. This book was released on 2014-08-27 with total page 1449 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is divided into four main sections thoroughly analyzing the use of nanomaterials for water, air and soil solutions, and emphasizing environmental risks. Providing background on nanomaterials' two-decade study, it discusses the characterization and application of unconventional disinfectants, called antimicrobial nanomaterials, which fall into three categories and, while seemingly harmless, have potential hazards if applied improperly. Special attention is given to the process of remediation, synthetics techniques, and properties of nanomaterials, with examples to which new and trained readers in the field can relate and understand. an interdisciplinary approach, aimed at scientists in physical chemistry, nanotechnology, and environmental sciences includes applications of non-conventional techniques in environmental protection furthers the development of applied nanoscience and nanotechnology suggests new industrial projects and university courses addressing nanotechnology in and for the environment includes applications for water, air and soil protection
Download or read book Green Nanomaterials written by Shakeel Ahmed and published by Springer Nature. This book was released on 2020-03-16 with total page 349 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book comprises a collection of chapters on advances in green nanomaterials. The book looks at ways to establish long‐term safe and sustainable forms of nanotechnology through implementation of nanoparticle biosynthesis with minimum impact on the ecosystem. The book looks at synthesis, processing, and applications of metal and metal oxide nanomaterials and also at bio-nanomaterials. The contents of this book will prove useful for researchers and professionals working in the field of nanomaterials and green technology.
Download or read book Radiochemical Analysis written by and published by . This book was released on 1964 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Handbook of Inpatient Cardiology written by Bryan J. Wells and published by Springer Nature. This book was released on 2020-07-22 with total page 545 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book serves as a pocket-sized resource to aid with the diagnosis and management of cardiovascular disease in the inpatient setting. Containing up-to-date information from guidelines and clinical trials, this book is the only handbook-style reference on cardiac care designed specifically for the hospitalist. The first section of the book covers cardiac pathology with an emphasis on evidence-based and guideline-based approaches to patient care. Each chapter focuses on a specific cardiovascular disease state such as acute coronary syndrome, atrial fibrillation, pulmonary hypertension, and aortic disease. The second section examines the differential diagnoses and recommended workup for common cardiac chief complaints including chest pain, palpitations, syncope, and dyspnea. The third and final section discusses indications and interpretation of commonly used cardiac procedures and imaging modalities. This book provides a concise review over a broad range of cardiovascular disease states in an accessible handbook-style to aid with the care of these patients. The Handbook of Inpatient Cardiology is an essential resource for physician hospitalists caring for cardiac patients on the medical ward in addition to cardiology physicians and trainees, affiliate providers, and students.
Download or read book Ionic Liquids as Green Solvents written by Robin D. Rogers and published by Amer Chemical Society. This book was released on 2003-01-01 with total page 599 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation FollowingIonic Liquids: Industrial Applications to Green Chemistry, SS #818, by the same editors, this book focuses on exciting new developments in ionic liquids.
