Of the societal ills which are recognized as present in the Western countries during the 1970's, pollution of air and water is among the first. Whether the breathing of noxious gases acts biochemically as a source of mental irritation is not yet known. But it is not in doubt that reduction of the grime, smog, fouled water, and acrid air would lead to an increase in a feeling of well-being. Nor is it speculative to state that a reversal of the present trend to poison the atmosphere and the water is essential if man is to survive in a technological society. It was partly the lack of realization of the intrinsic nature of over potential in electrochemical reactions, * and hence the failure of the early fuel cells to come up to expectations, which led engineers at the turn of the century to rely upon the combustion of oil and coal for the production of energy, with the associated era of increasing atmospheric pollution.

This book had its nucleus in some lectures given by one of us (J. O’M. B. ) in a course on electrochemistry to students of energy conversion at the University of Pennsyl- nia. It was there that he met a number of people trained in chemistry, physics, biology, metallurgy, and materials science, all of whom wanted to know something about electrochemistry. The concept of writing a book about electrochemistry which could be understood by people with very varied backgrounds was thereby engendered. The lectures were recorded and written up by Dr. Klaus Muller as a 293-page manuscript. At a later stage, A. K. N. R. joined the effort; it was decided to make a fresh start and to write a much more comprehensive text. Of methods for direct energy conversion, the electrochemical one is the most advanced and seems the most likely to become of considerable practical importance. Thus, conversion to electrochemically powered transportation systems appears to be an important step by means of which the difficulties of air pollution and the effects of an increasing concentration in the atmosphere of carbon dioxide may be met. Cor- sion is recognized as having an electrochemical basis. The synthesis of nylon now contains an important electrochemical stage. Some central biological mechanisms have been shown to take place by means of electrochemical reactions. A number of American organizations have recently recommended greatly increased activity in training and research in electrochemistry at universities in the United States.

This book concentrates on the electrochemistry/environment relationship including, among others, chapters on design and operation of electrochemical reactors and separators, process simulation, development and scale-up, optimization and control of electrochemical processes applied to environmental problems, also including economic analysis, description of unique current and future applications, in addition to basic research into developing new technologies. It is hoped that this volume will be considered interesting and extremely timely to specialists in electrochemistry and environmental sciences.

The text Modern Electrochemistry (authored by J. O'M. Bockris and A. K. N. Reddy and published by Plenum Press in 1970) was written between 1967 and 1969. The concept for it arose in 1962 in the Energy Conversion Center at the University of Pennsylvania, and it was intended to act as a base for interdisciplinary students and mature scientists~hemists, physicists, biologists, metallurgists, and engineers-who wanted to know about electrochemical energy conversion and storage. In writing the book, the stress, therefore, was placed above all on lucidity in teaching physical electrochemistry from the beginning. Although this fundamentally undergraduate text continues to find purchasers 20 years after its birth, it has long been clear that a modernized edition should be written, and the plans to do so were the origin of the present book. However, if a new Bockris and Reddy was to be prepared and include the advances of the last 20 years, with the same degree of lucidity as characterized the first one, the depth of the development would have to be well short of that needed by professional electrochemists.

Wastewater treatment technology is undergoing a profound transformation due to the fundamental changes in regulations governing the discharge and disposal of h- ardous pollutants. Established design procedures and criteria, which have served the industry well for decades, can no longer meet the ever-increasing demand. Toxicity reduction requirements dictate in the development of new technologies for the treatment of these toxic pollutants in a safe and cost-effective manner. Fo- most among these technologies are electrochemical processes. While electrochemical technologies have been known and utilized for the tre- ment of wastewater containing heavy metal cations, the application of these p- cesses is only just a beginning to be developed for the oxidation of recalcitrant organic pollutants. In fact, only recently the electrochemical oxidation process has been rec- nized as an advanced oxidation process (AOP). This is due to the development of boron-doped diamond (BDD) anodes on which the oxidation of organic pollutants is mediated via the formation of active hydroxyl radicals.