©2004 CRC Press LLC ©2004 CRC Press LLC ©2004 CRC Press LLC To my wife, Rosa Maria, and to my son Fernando ©2004 CRC Press LLC ©2004 CRC Press LLC Preface Today, ozone is considered as an alternative oxidant-disinfectant agent with multiple possibilities of application in water, air pollution, medicine, etc. Particularly, in water treatment it has many abilities to disinfect, oxidize, or to be combined with other technologies and reagents. Much of the information about these general aspects of ozone has been reported in excellent works like that of Langlais et al. (1991). There is another aspect, however, that the literature has not dealt with sufficiently — the ozonation kinetics of compounds in water, especially those organic compounds usually considered water pollutants. About this, on the contrary, there are many works published in scientific journals like Ozone Science and Engineering , Water Research , Industrial and Engineering Chemistry Research , etc., that present simple examples of the multiple possibilities of ozone in water and wastewater treatment as far as the kinetics is concerned. I thought that this wide array of ozone kinetic information deserved to be published in a unique book in which the many aspects of this subject can be grouped together for a better understanding of its fundamentals through a general overview. For more than 20 years I have been working on the use of ozone to oxidize organic compounds, both in organic and, especially, aqueous media. Results of this research work has generated different doctoral theses on the ozonation of dyes, phenols, herbicides, polynuclear aromatic hydrocarbons, wastewater, etc, and have also resulted in more than 100 papers in different scientific journals such as those cited above. Also, for many years I have been lecturing on ozonation kinetics in doctoral courses at the University of Extremadura (Badajoz, Spain). As a result of this accumulated experience, I can affirm that the multiple possibilities of ozone for application in water and wastewater treatment make the study of the ozonation kinetics a challenging subject in which theory and practice can be simultaneously examined. The work presented here represents a compilation of study throughout my years in this field. This book is intended for both undergraduate and postgraduate students, teach- ers, and professionals of water and wastewater treatment. Students who want to get involve in the world of ozone application in water need to know the many aspects of the subject covered here, including absorption or solubility of ozone, stability or decomposition, reactivity, kinetic regime of absorption, ozonation kinetics, and reactor modeling. Those practicing ozone water treatment, that is, professionals in the ozonation processes field, will be able to add to their fund of knowledge with the advanced information it contains. Finally, the book can also be a tool for teaching in which the many fundamentals of chemistry, reaction mechanisms, and, particu- larly, chemical engineering kinetics and heterogeneous kinetics can be verified from examining the results of the ozonation of organic compounds in water. The various subjects that affect the ozone kinetics in water are presented in 11 chapters. Chapter 1 gives a short history of ozone in nature and tells us about the electronic structure of the ozone molecule which is responsible for the ozone reactivity. ©2004 CRC Press LLC In Chapter 2 the chemistry of ozone reactions in water is reviewed by studying the two known reaction types through which ozone acts in water: the direct and indirect or free radical reactions. Chapter 3 focuses on the kinetics of the direct ozone reactions. It is explained that these studies can be developed through experimental homogeneous and heterogeneous ozone reactions. Chapter 4 and Chapter 5 continue with studies on direct ozone reaction kinetics, but they exclusively deal with heterogeneous gas–liquid reaction kinetics which represents the way ozone is applied in water and wastewater treatment — that is, in gas form. Chapter 4 presents the fundamentals of the kinetics of these reactions. It gives detailed explanations about the kinetic equations of gas–liq- uid reactions that are later applied to ozone direct reaction kinetic studies in Chapter 5. Chapter 5 covers examples of kinetic works on ozone gas–water reactions, starting with the necessary tools to accomplish this task: the properties of ozone in water, such as solubility and diffusivity. Also in Chapter 5, the ozone kinetic studies are presented according to the kinetic regimes of ozone absorption that, once established, allow the rate constant and mass transfer coefficients to be determined. Chapter 6 is dedicated to wastewater ozonation reactions. Thus, classification of wastewater with regard to its reactivity with ozone, characterizing parameters, the importance of pH, and the influence of ozonation on biological processes are treated in Chapter 6. The second part of Chapter 6 addresses to the kinetics of wastewater ozone reactions and some insights are given to carry out these studies experimentally. Chapters 7 to 9 deal with the kinetics of indirect ozone reactions that can also be named as ozone involving advanced oxidation reactions: ozone alone and ozone combined with hydrogen peroxide and UV radiation. Chapter 7 deals with the indirect reactions coming from the decomposition of ozone (without the addition of hydrogen peroxide or UV radiation). The chapter begins with a study on the relative importance of ozone direct and the ozone decomposition reactions whose results are fundamental to establishing the overall kinetics of any ozone–compound B reaction. Also in Chapter 7, methods to determine the rate constant of the reactions between the hydroxyl free radical and a compound B, and characteristic relationships of natural water to ozone reactivity are given. Chapter 8 presents the kinetic study of ozone–hydrogen peroxide processes. Again, aspects related to the rate constant determination, kinetic regimes, and competition with direct ozone reactions are developed. Chapter 9 focuses on the UV radiation/ozone processes. It first deals with the direct photolytic and UV radiation/hydrogen peroxide processes, the latter because it is also present when ozone and UV radiation are simultaneously applied. Chapter 9 includes methods to determine quantum yields, rate constants of hydroxyl radical reactions, and multiple aspects on the relative importance of different reac- tions; ozone direct reactions; ozone–peroxide reactions; and ozone direct photolysis, among other subjects. Chapter 10 presents the state of the art of another type of ozone action: heterogeneous catalytic ozonation. Although dating from the 1970s, this field has advanced significantly in the last decade which has witnessed considerable increase in work on heterogeneous catalytic ozonation. In Chapter 10, the fun- damentals of the kinetics of these gas–liquid–solid catalytic reactions are first given and then applications to the catalytic ozonation of compounds in water. Also, a commented and extensive list (through tables) of studies already pub- lished on this ozone action is offered. Finally, Chapter 11 presents the kinetic modeling of ozone reactions. Chapter 11 starts with a detailed classification on possible ways of ozone kinetic modeling according to the different kinetic ©2004 CRC Press LLC regimes of ozone absorption. Mathematical models are presented together with the way in which they can be solved, with ozone literature examples. The study focuses on studies of ozone reactions on model compounds, which are more related to drinking water treatment and wastewater ozonation. The book’s appen- dix gives mathematical tools, concepts on ideal reactors and actinometry, and nonideal flow studies needed to solve and understand the ozonation kinetic examples previously developed. ©2004 CRC Press LLC About the Author Fernando Juan Beltran Novillo received his doctorate in chemistry in 1982 from the University of Extremadura in Badajoz, Spain, and in 1986 he became Profesor Titular in Chemical Engineering at the University of Extremadura. In 1985 and 1986 he did postdoctoral studies at the Laboratoire de Chimie de l’eau et de Nuisances at the University of Poitiers (France) where he worked with Professors Doré, Legube, and Croué on the ozonation of natural fulvic substances and the effect on trihalomethane formation. In 1988 and 1989, he worked at the School of Chemical Engineering, Bath University (England) on catalytic combustion of PCBs and catalytic wet air oxidation with Professors Kolaczkowski and Crittenden . He spent another research stay in the Environmental Science and Engi- neering Department at the University of North Carolina in 1991, working with Professor Glaze on the UV radiation/hydrogen peroxide oxidation system. He became Catedratico (Professor) in Chemical Engineering in 1992 at the University of Extremadura. In 1993, he was Visiting Professor at the University of Bath (England). Doctor Beltran has codirected 13 doctoral theses mainly dealing with the ozo- nation kinetics of model compounds and wastewaters, and has published more than 100 papers on ozonation studies, most of them on kinetics. He is a member of the International Ozone Association, a member of the editorial board of Ozone Science and Engineering and International Water Quality . He has collaborated in the peer reviewing process of many scientific and engineering jour- nals such as Ozone Science and Engineering , Industrial Engineering Chemistry Research , Environmental Science and Technology , Water Research , and Applied Catalysis B . At present, he teaches chemical reaction engineering for undergraduate students and ozone reaction kinetics in water for postgraduate students at the University of Extremadura, where he is also director of a research group on water treatment. ©2004 CRC Press LLC ©2004 CRC Press LLC [...]... Absorption 11 .3 Case of Intermediate or Moderate Kinetic Regime of Ozone Absorption 11 .4 Time Regimes in Ozonation 11 .5 Influence of the Type of Water and Gas Flows 11 .6 Mathematical Models 11 .6 .1 Slow Kinetic Regime 11 .6 .1. 1 Both Gas and Water Phases in Perfect Mixing Flow 11 .6 .1. 2 Both Gas and Water Phases in Plug Flow 11 .6 .1. 3 The Water Phase in Perfect Mixing Flow and the Gas Phase in Plug Flow 11 .6 .1. 4... Flow 11 .6.2.3 Both the Gas and Water Phases in Plug Flow 11 .6.3 The Moderate Kinetic Regime: A General Case 11 .7 Examples of Kinetic Modeling for Model Compounds 11 .8 Kinetic Modeling of Wastewater Ozonation 11 .8 .1 Case of Slow Kinetic Regime: Wastewater with Low COD 11 .8 .1. 1 Kinetic Modeling of Wastewater Ozonation without Considering a Free Radical Mechanism 11 .8 .1. 2 Kinetic Modeling of Wastewater. .. LLC Contents Chapter 1 Introduction 1. 1 Ozone in Nature 1. 2 The Ozone Molecule References Chapter 2 Reactions of Ozone in Water 2 .1 2.2 2.3 2.4 2.5 Oxidation–Reduction Reactions Cycloaddition Reactions Electrophilic Substitution Reactions Nucleophilic Reactions Indirect Reactions of Ozone 2.5 .1 The Ozone Decomposition Reaction References Chapter 3 Kinetics of the Direct Ozone Reactions 3 .1 Homogeneous... 11 .6 .1. 4 The Water Phase as N Perfectly Mixed Tanks in Series and the Gas Phase in Plug Flow ©2004 CRC Press LLC 11 .6 .1. 5 Both the Gas and Water Phases as N and N¢ Perfectly Mixed Tanks in Series 11 .6 .1. 6 Both the Gas and Water Phases with Axial Dispersion Flow 11 .6.2 Fast Kinetic Regime 11 .6.2 .1 Both the Water and Gas Phases in Perfect Mixing 11 .6.2.2 The Gas Phase in Plug Flow and the Water Phase... LLC Chapter 10 Heterogeneous Catalytic Ozonation 10 .1 Fundamentals of Gas–Liquid–Solid Catalytic Reaction Kinetics 10 .1. 1 Slow Kinetic Regime 10 .1. 2 Fast Kinetic Regime or External Diffusion Kinetic Regime 10 .1. 3 Internal Diffusion Kinetic Regime 10 .1. 4 General Kinetic Equation for Gas–Liquid–Solid Catalytic Reactions 10 .1. 5 Criteria for Kinetic Regimes 10 .2 Kinetics of the Heterogeneous Catalytic Ozone. .. Catalytic Reaction 10 .4 Kinetics of Semiconductor Photocatalytic Processes 10 .4 .1 Mechanism of TiO2 Semiconductor Photocatalysis 10 .4.2 Langmuir–Hinshelwood Kinetics of Semiconductor Photocatalysis 10 .4.3 Mechanism and Kinetics of Photocatalytic Ozonation References Chapter 11 Kinetic Modeling of Ozone Processes 11 .1 Case of Slow Kinetic Regime of Ozone Absorption 11 .2 Case of Fast Kinetic Regime of Ozone. .. using ozone and its effect on the wastewater biodegradability, J Agric Food Chem., 47, 3 911 –3 918 , 19 99 29 Trambarulo, R et al., The molecular structure, dipole moment, and g factor of ozone from its microwave spectrum, J Phys Chem., 21, 8 51 855, 19 53 30 Nebel, C., Ozone, in Kirk-Othmer: Encyclopedia of Chemical Technology, 3rd ed., Vol 16 , John Wiley & Sons, New York, 19 81, 683– 713 31 Perry, R.H and. .. Film Theory 4.2 .1. 1 Irreversible First-Order or Pseudo First-Order Reactions 4.2 .1. 2 Irreversible Second-Order Reactions 4.2 .1. 3 Series-Parallel Reactions 4.2.2 Danckwerts Surface Renewal Theory 4.2.2 .1 First-Order or Pseudo First-Order Reactions 4.2.2.2 Irreversible Second-Order Reactions 4.2.2.3 Series-Parallel Reactions ©2004 CRC Press LLC 4.2.3 Influence of Gas Phase Resistance 4.2.3 .1 Slow Kinetic... Value –2 51 11 2 54.62 12 .1 1.658 higher than air 1. 71 gcm–3 at 18 3ºC 436 2,980 33,880 38,860 2.07 At the boiling point temperature bAt 1 atm and 25ºC cAt pH = 0 Source: Perry, R.H and Green, D.W., Perry’s Chemical Engineers Handbook, 7th ed., McGraw-Hill, New York, 19 97 With permission ©2004 CRC Press LLC REFERENCES 1 Rook, J.J., Formation of haloforms during chlorination of natural waters, Water Treat... Water Res., 32, 2357–2364, 19 98 26 Boere, J.A., Combined use of ozone and granular activated carbon (GAC) in potable water treatment; Effects on GAC quality after reactivation, Ozone Sci Eng., 14 , 12 3 13 7, 19 92 27 Beltrán, F.J et al., Improvement of domestic wastewater sedimentation through ozonation, Ozone Sci Eng., 21, 605– 614 , 19 99 28 Beltrán, F.J et al., Wine-distillery wastewater degradation 1 . Regime of Ozone Absorption 11 .4 Time Regimes in Ozonation 11 .5 Influence of the Type of Water and Gas Flows 11 .6 Mathematical Models 11 .6 .1 Slow Kinetic Regime 11 .6 .1. 1 Both Gas and Water Phases. Flow 11 .6.2 Fast Kinetic Regime 11 .6.2 .1 Both the Water and Gas Phases in Perfect Mixing 11 .6.2.2 The Gas Phase in Plug Flow and the Water Phase in Perfect Mixing Flow 11 .6.2.3 Both the Gas and Water. Phases in Perfect Mixing Flow 11 .6 .1. 2 Both Gas and Water Phases in Plug Flow 11 .6 .1. 3 The Water Phase in Perfect Mixing Flow and the Gas Phase in Plug Flow 11 .6 .1. 4 The Water Phase as N Perfectly