Applied Sonochemistry

Power ultrasound has been used for many years in two specific industrial areas: cleaning and plastic welding. Over the last ten years an increasing interest has been shown in its potential for use over a much wider range of chemistry and processing which has been grouped together under the general title of sonochemistry. Most of these uses depend on the generation of acoustic cavitation in liquid media but this text, while underlining the importance of the physics and mathematics of cavitation, mainly concentrates on applications of the technology. After an introduction to the topic and some historical background to the uses of power ultrasound the general principles of acoustic cavitation are explored including some background physics, bubble dynamics and factors which influence cavitation. The remainder of the book incorporates a series of applications of sonochemistry which illustrate the types of physical and chemical effects of ultrasonically induced cavitation which will interest chemists and engineers alike. Amongst the major topics included are chemical synthesis, environmental protection and remediation of water, sewage and soils, polymer synthesis and processing, electrochemistry including both analytical and synthetic aspects and plating. The final chapter reviews the range of ultrasonic equipment available in the laboratory and the progress made towards the scale-up of sonochemistry. The level is introductory to semi-advanced and no topic has been taken to a particularly specialist level since it is intended that this should be of general interest to readers with a scientific background.

In the 1980’s sonochemistry was considered to be a rather restricted branch of chemistry involving the ways in which ultrasound could improve synthetic procedures, predominantly in heterogeneous systems and particularly for organometallic reactions. Within a few years the subject began to expand into other disciplines including food technology, environmental protection and the extraction of natural materials. Scientific interest grew and led to the formation of the European Society of Sonochemistry in 1990 and the launch of a new journal Ultrasonics Sonochemistry in 1994. The subject continues to develop as an exciting and multi-disciplinary science with the participation of not only chemists but also physicists, engineers and biologists. The resulting cross-fertilisation of ideas has led to the rapid growth of interdisciplinary research and provided an ideal way for young researchers to expand their knowledge and appreciation of the ways in which different sciences can interact. It expands scientific knowledge through an opening of the closed doors that sometimes restrict the more specialist sciences. The journey of exploration in sonochemistry and its expansion into new fields of science and engineering is recounted in "Sonochemistry Evolution and Expansion" written by two pioneers in the field. It is unlike other texts about sonochemistry in that it follows the chronological developments in several very different applications of sonochemistry through the research experiences of the two authors Tim Mason and Mircea Vinatoru. Designed for chemists and chemical engineers Written by two experts and practitioners in the subject Volume 1 covers the historical background and evolution of sonochemistry Volume 2 explains the wider applications and expansion of the subject VOLUME 2 Applications and Developments Volume 2 contains six chapters which detail the developments of sonochemistry in fields which continue to attract considerable research and development interest from academia and industry. The topics range from the important developments in chemical synthesis through food technology and materials processing to therapeutic ultrasound. The authors have made contributions to all of these and so the content is written in a way which should be understandable to readers whose expertise may not necessarily be in the individual topic. Each of the applications and developments described help to illustrate not only the diverse nature of sonochemistry but also the unifying theme of the effects of acoustic cavitation on a wide range of procedures.

This book provides an introduction to the fundamental and applied aspects of sonochemistry, discussing a number of basic concepts in sonochemistry, such as how ultrasonic waves interact with gas bubbles in liquids to generate cavitation, and how the high temperatures generated within cavitation bubbles could be estimated. It explains how redox radicals are produced and how to make use of both the physical and chemical forces generated during cavitation for various applications. Intended for academic researchers, industry professionals as well as undergraduate and graduate students, especially those starting on a new research topic or those new to the field, it provides a clear understanding of the concepts and methodologies involved in ultrasonic and sonochemistry.

This book provides informative, useful, and stimulating reading on the topic of organic sonochemistry – the core of ultrasound-based applications. Given the increasing interest in new and improved technologies, allied to their green and sustainable character (not always a valid premise), there is a great attraction for organic chemists to apply these protocols in synthesis and process chemistry. Unfortunately, as with other enabling technologies, many researchers new to the field have received a simple and dishonest message: just switch on! Therefore a significant portion of sonochemical syntheses lack reproducibility (surprisingly cavitation control and/or ultrasonic parameters are omitted) and the actual role of sonication remains uncertain. While this book does not provide a detailed description of fundamentals, the introductory remarks highlight the importance of cavitational effects and their experimental control. It presents a number of concepts of sonochemical reactivity and empirical rules with pertinent examples, often from classical and recent literature. It then focuses on scenarios of current interest where organic chemistry, and synthesis in particular, may benefit from sonication in terms of both chemical and mechanical activation. The “sustainable corner” of this field is largely exemplified through concepts like atom economy, renewable sources, wasteless syntheses, and benign solvents as reaction media. This book is useful for both researchers and graduate students, especially those familiar with the field of sonochemistry and applications of ultrasound in general. However, it is also of interest to a broader audience as it discusses the fundamentals, techniques, and experimental skills necessary for scientists wishing to initiate the use of ultrasound in their domain of expertise.

The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field.

Ultrasound in Environmental Protection focuses on one of the more significant developments in the subject - environmental remediation - providing an overview on both the fundamentals and applications of ultrasound in environmental protection, incorporating recent research and state-of-the-art information on the scientific basis, modes of use, and engineering developments. A broad spectrum of topics are covered: reactor design, sonochemical pollutant degradation, integrated unltrasonic/ biological treatment, ultrasound in disinfection, leaching by ultrasound, and ultrasonically enhanced removal of suspended solids. Ultrasound is generated and applied at frequencies from 20 kHz to several MHz. The physio-chemical parameters of the sonicated media, reactor design, applied intensity, and duration of sonication, dramatically influence the effects that can be achieved. It is hoped that this compilation will contribute to a better understanding and further development of sonochemistry as a clean technology not only for environmental remediation but also more generally. The foundation of this compilation was formed during a workshop that was held at the Technical University of Hamburg-Harburg, Germany, in March 1999. This was the first workshop to be devoted to 'Ultrasound in Environmental Engineering' and brought together experience and knowledge from a broad spectrum of disciplines including chemistry, biology, engineering, equipment manufacturing, and plant design.

Despite the fact that chemical applications of ultrasound are now widely acknowledged, a detailed presentation of inorganic systems covering nano-particles, catalysis, aqueous chemistry of metallic solutions and their redox characteristics, both from a theoretical and experimental perspective has eluded researchers of this field. Theoretical and Experimental Sonochemistry Involving Inorganic Systems fills this gap and presents a concise and thorough review of this fascinating area of Sonochemistry in a single volume.

This book discusses the ultrasonic synthesis, characterization and application of various nanoparticles, as well as the ultrasonic synthesis of metal and inorganic nanoparticles such as noble metals, transition metals, semiconductors, nanocomposites, alloys and catalysts. In addition, it describes the engineering of micro- and nanosystems using ultrasound-responsive biomolecules. In acoustic cavitation, unique phenomena based on bubbles dynamics, extreme high-temperature and pressure conditions, radical reactions, extreme heating and cooling rates, strong shockwaves, and microstreaming are generated, and under certain conditions, mist generation (atomization of a liquid) is effectively induced by ultrasonic irradiation. These unique phenomena can be used to produce various high-performance functional metal and inorganic nanoparticles. Nanoparticles and nanomaterials are key materials in advancing nanotechnology and as such ultrasound and sonochemical techniques for producing nanoparticles and nanomaterials have been actively studied for the last two decades. Although a few professional books related to “ultrasound” and “nanomaterials” have been published, these mainly target professional researchers. This book covers this topic in a way that appeals to graduate students, researchers and engineers.