Ultraviolet photocatalytic oxidation technology for indoor volatile organic compound removal: A critical review with particular focus on byproduct formation and modeling.
TL;DR: In this paper, a case study was conducted to develop a support vector machine (SVM) classification model with good accuracy, and challenging compound types, inlet concentrations, and air velocity were found to be the main parameters affecting the applicability of UV-PCO.
About: This article is published in Journal of Hazardous Materials.The article was published on 2022-01-05. It has received 13 citations till now. The article focuses on the topics: HVAC & Photocatalysis.
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TL;DR: In this paper , an urchin-like Co x Cu 1-x O photocatalyst with a visible light-triggered bandgap and high surficial properties using nanotechnology, doping, and chemical activation approaches is presented.
13 citations
TL;DR: In this article , a review of the phytoremediation of formaldehyde in indoor air is presented, where the main topics of the review are, mechanism of PHYTHOREmediation, plants and their benefits, plant material in formaldehyde remediation, and airtight environmental and health issues.
Abstract: Abstract Formaldehyde evolves from various household items and is of environmental and public health concern. Removal of this contaminant from the indoor air is of utmost importance and currently, various practices are in the field. Among these practices, indoor plants are of particular importance because they help in controlling indoor temperature, moisture, and oxygen concentration. Plants and plant materials studied for the purpose have been reviewed hereunder. The main topics of the review are, mechanism of phytoremediation, plants and their benefits, plant material in formaldehyde remediation, and airtight environmental and health issues. Future research in the field is also highlighted which will help new researches to plan for the remediation of formaldehyde in indoor air. The remediation capacity of several plants has been tabulated and compared, which gives easy access to assess various plants for remediation of the target pollutant. Challenges and issues in the phytoremediation of formaldehyde are also discussed. Novelty statement: Phytoremediation is a well-known technique to mitigate various organic and inorganic pollutants. The technique has been used by various researchers for maintaining indoor air quality but its efficiency under real-world conditions and human activities is still a question and is vastly affected relative to laboratory conditions. Several modifications in the field are in progress, here in this review article we have summarized and highlighted new directions in the field which could be a better solution to the problem in the future. Graphical Abstract
6 citations
TL;DR: In this paper , the concentration and associated health risks of heavy metals (Cd, Cr, Pb, Cu, Fe, Mn, and Zn), biological pollutants, and their risk to human health were assessed using air condition (AC) filter dust samples.
Abstract: High levels of potentially toxic metals and microbes in the atmosphere, especially indoor air, may severely threaten human health. Therefore, the concentration and associated health risks of heavy metals (Cd, Cr, Pb, Cu, Fe, Mn, and Zn), biological pollutants, and their risk to human health were assessed using air condition (AC) filter dust samples. Samples were collected from five locations representing agricultural, industrial, and residential settings of the Eastern Province, Kingdom of Saudi Arabia. The levels of trace metals varied considerably among sampling areas, with the highest levels of Cr and Cd recorded in the industrial area sites, followed by the agricultural and residential sites. The highest levels of Pb and Fe were found in the agricultural area sites, followed by the industrial and residential area sites. Among all the metals Cd, Cr, and Pb, showed a considerable health risk through a dermal pathway, and health risks for children from indoor dust exposure were higher compared to adults. Among the sites, the highest hazard quotient for these metals was found for Al-Qatif industrial area sites, and among the metals, it was the highest for Cd. The cancer risk from the metals contained in AC filter dust was negligible. Samples collected from agricultural and industrial area sites were substantially contaminated with bacteria and fungi, respectively. Bacterial contaminants were mostly Gram-negative, with considerable antibiotic resistance and hemolytic activity. Thus, indoor air quality assessed by AC filter dust depicted that the trace heavy metals and microorganisms could pose a considerable health risk for long-term exposure. Furthermore, this study demonstrated that AC filter dust could be a unique and reliable test sample for indoor environment assessment.
3 citations
TL;DR: In this article , the authors investigated the interactions of limonene and carvone with TiO2, a component of paint and self-cleaning surfaces, at 297 ± 1 K with FTIR spectroscopy and force field-based molecular dynamics.
Abstract: Limonene, a monoterpene, found in cleaning products and air fresheners can interact with a variety of surfaces in indoor environments. An oxidation product of limonene, carvone, has been reported to cause contact allergens. In this study, we have investigated the interactions of limonene and carvone with TiO2, a component of paint and self-cleaning surfaces, at 297 ± 1 K with FTIR spectroscopy and force field-based molecular dynamics and ab initio simulations. The IR absorption spectra and computational methods show that limonene forms π-hydrogen bonds with the surface O-H groups on the TiO2 surface and that carvone adsorbs on the TiO2 surface through a variety of molecular interactions including through carbonyl oxygen atoms with Ti4+ surface atoms, O-H hydrogen bonding (carbonyl O⋯HO) and π-hydrogen bonds with surface O-H groups. Furthermore, we investigated the effects of relative humidity (RH) on the adsorption of limonene and carvone on the TiO2 surface. The spectroscopic results show that the adsorbed limonene can be completely displaced by water at a relative humidity of ca. 50% RH (∼2 MLs of water) and that 25% of carvone is displaced at ca. 67% RH, which agrees with the calculated free energies of adsorption which show carvone more strongly adsorbs on the surface relative to limonene and thus would be harder to displace from the surface. Overall, this study shows how a monoterpene and its oxidation product interact with TiO2 and the impact of relative humidity on these interactions.
2 citations
TL;DR: In this article , the authors provide a detailed description of the primary challenges and potential solutions encountered in scaling up photocatalytic systems for use in large-scale water and air purification and solar hydrogen production.
1 citations
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TL;DR: A review of the status of research on photocatalytic oxidation (PCO) purification of VOCs in indoor air can be found in this paper, where some recommendations are made for future work to evaluate the performance of PCO catalysts, to reduce the generation of harmful intermediates and to design new PCO reactors with integrated UV source and reaction surface.
741 citations
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01 Jan 1977
TL;DR: In this article, the authors present a detailed discussion of common HVAC units and their dimensions, as well as the basic concerns of IAQ, such as comfort, health, and environment.
Abstract: Preface About the Authors Symbols 1. Introduction 1-1 Historical Notes 1-2 Common HVAC Units and Dimensions 1-3 Fundamental Physical Concepts 1-4 Additional Comments References Problems 2. Air-Conditioning Systems 2-1 The Complete System 2-2 System Selection and Arrangement 2-3 HVAC Components and Distribution Systems 2-4 Types of All-Air Systems 2-5 Air-and-Water Systems 2-6 All-Water Systems 2-7 Decentralized Cooling and Heating 2-8 Heat Pump Systems 2-9 Heat Recovery Systems 2-10 Thermal Energy Storage References Problems 3. Moist Air Properties and Conditioning Processes 3-1 Moist Air and the Standard Atmosphere 3-2 Fundamental Parameters 3-3 Adiabatic Saturation 3-4 Wet Bulb Temperature and the Psychrometric Chart 3-5 Classic Moist Air Processes 3-6 Space Air Conditioning Design Conditions 3-7 Space Air Conditioning Off-Design Conditions References Problems 4. Comfort and Health Indoor Environmental Quality 4-1 Comfort Physiological Considerations 4-2 Environmental Comfort Indices 4-3 Comfort Conditions 4-4 The Basic Concerns of IAQ 4-5 Common Contaminants 4-6 Methods to Control Humidity 4-7 Methods to Control Contaminants References Problems 5. Heat Transmission in Building Structures 5-1 Basic Heat-Transfer Modes 5-2 Tabulated Overall Heat-Transfer Coefficients 5-3 Moisture Transmission References Problems 6. Space Heating Load 6-1 Outdoor Design Conditions 6-2 Indoor Design Conditions 6-3 Transmission Heat Losses 6-4 Infiltration 6-5 Heat Losses from Air Ducts 6-6 Auxiliary Heat Sources 6-7 Intermittently Heated Structures 6-8 Supply Air For Space Heating 6-9 Source Media for Space Heating 6-10 Computer Calculation of Heating Loads References Problems 7. Solar Radiation 7-1 Thermal Radiation 7-2 The Earth's Motion About the Sun 7-3 Time 7-4 Solar Angles 7-5 Solar Irradiation 7-6 Heat Gain Through Fenestrations 7-7 Energy Calculations References Problems 8. The Cooling Load 8-1 Heat Gain, Cooling Load, and Heat Extraction Rate 8-2 Application of Cooling Load Calculation Procedures 8-3 Design Conditions 8-4 Internal Heat Gains 8-5 Overview of the Heat Balance Method 8-6 Transient Conduction Heat Transfer 8-7 Outside Surface Heat Balance Opaque Surfaces 8-8 Fenestration Transmitted Solar Radiation 8-9 Interior Surface Heat Balance Opaque Surfaces 8-10 Surface Heat Balance Transparent Surfaces 8-11 Zone Air Heat Balance 8-12 Implementation of the Heat Balance Method 8-13 Radiant Time Series Method 8-14 Implementation of the Radiant Time Series Method 8-15 Supply Air Quantities References Problems 9. Energy Calculations and Building Simulation 9-1 Degree-Day Procedure 9-2 Bin Method 9-3 Comprehensive Simulation Methods 9-4 Energy Calculation Tools 9-5 Other Aspects of Building Simulation References Problems 10. Flow, Pumps, and Piping Design 10-1 Fluid Flow Basics 10-2 Centrifugal Pumps 10-3 Combined System and Pump Characteristics 10-4 Piping System Fundamentals 10-5 System Design 10-6 Steam Heating Systems References Problems 11. Space Air Diffusion 11-1 Behavior of Jets 11-2 Air-Distribution System Design References Problems 12. Fans and Building Air Distribution 12-1 Fans 12-2 Fan Relations 12-3 Fan Performance and Selection 12-4 Fan Installation 12-5 Field Performance Testing 12-6 Fans and Variable-Air-Volume Systems 12-7 Air Flow in Ducts 12-8 Air Flow in Fittings 12-9 Accessories 12-10 Duct Design General 12-11 Duct Design Sizing References Problems 13. Direct Contact Heat and Mass Transfer 13-1 Combined Heat and Mass Transfer 13-2 Spray Chambers 13-3 Cooling Towers References Problems 14. Extended Surface Heat Exchangers 14-1 The Log Mean Temperature Deficiency (LMTD) Method 14-2 The Number of Transfer Units (NTU) Method 14-3 Heat Transfer-Single-Component Fluids 14-4 Transport Coefficients Inside Tubes 14-5 Transport Coefficients Outside Tubes and Compact Surfaces 14-6 Design Procedures for Sensible Heat Transfer 14-7 Combined Heat and Mass Transfer References Problems 15. Refrigeration 15-1 The Performance of Refrigeration Systems 15-2 The Theoretical Single-Stage Compression Cycle 15-3 Refrigerants 15-4 Refrigeration Equipment Components 15-5 The Real Single-Stage Cycle 15-6 Absorption Refrigeration 15-7 The Theoretical Absorption Refrigeration System 15-8 The Aqua-Ammonia Absorption System 15-9 The Lithium Bromide-Water System References Problems Appendix A. Thermophysical Properties Table A-1a. Properties of Refrigerant 718 (Water-Steam) English Units Table A-1b. Properties of Refrigerant 718 (Water-Steam) SI Units Table A-2a. Properties of Refrigerant 134a (1,1,1,2-Tetrafluoroethane) English Units Table A-2b. Properties of Refrigerant 134a (1,1,1,2-Tetrafluoroethane) SI Units Table A-3a. Properties of Refrigerant 22 (Chlorodifluoromethane) English Units Table A-3b. Properties of Refrigerant 22 (Chlorodifluoromethane) SI Units Table A-4a. Air English Units Table A-4b. Air SI Units Appendix B. Weather Data Table B-1a. Heating and Cooling Design Conditions United States, Canada, and the World English Units Table B-1b. Heating and Cooling Design Conditions United States, Canada, and the World SI Units Table B-2. Annual BinWeather Data for Oklahoma City,OK Table B-3. Annual Bin Weather Data for Chicago, IL Table B-4. Annual Bin Weather Data for Denver, CO Table B-5. Annual Bin Weather Data for Washington, DC Appendix C. Pipe and Tube Data Table C-1. Steel Pipe Dimensions English and SI Units Table C-2. Type L Copper Tube Dimensions English and SI Units Appendix D. Useful Data Table D-1. Conversion Factors Appendix E: Charts Chart 1a. ASHRAE Psychrometric Chart No. 1 (IP) (Reprinted by permission of ASHRAE.) Chart 1b. ASHRAE Psychrometric Chart No. 1 (SI) (Reprinted by permission of ASHRAE.) Chart 1Ha. ASHRAE Psychrometric Chart No. 4 (IP) (Reprinted by permission of ASHRAE.) Chart 1Hb. ASHRAE Psychrometric Chart No. 6 (SI) (Reprinted by permission of ASHRAE.) Chart 2. Enthalpy-concentration diagram for ammonia-water solutions (From Unit Operations by G. G. Brown, Copyright (c)1951 by John Wiley & Sons, Inc.) Chart 3. Pressure-enthalpy diagram for refrigerant 134a (Reprinted by permission.) Chart 4. Pressure-enthalpy diagram for refrigerant 22 (Reprinted by permission.) Chart 5. Enthalpy-concentration diagram for Lithium Bromide-water solutions (Courtesy of Institute of Gas Technology, Chicago IL.) Index
712 citations
TL;DR: In this paper, the authors present a comprehensive literature review of TiO2 modification techniques that include approaches for overcoming the inherentTiO2 limitations and improving the photocatalytic degradation of VOCs.
667 citations
TL;DR: In this article, photocatalyzed degradations of trace levels of various oxygenates and an aromatic in air were carried out using near-UV-illuminated titanium dioxide (anatase) powder.
498 citations