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Photoelectronics, Photocalysis and Photoreactors
Book Reviews Mixing in the Process Industries. Edited by N. HARNBY, F. EDWARDS and A. W. NIENOW. 372 pp.. L37.50
M.
The book presents a comprehensive overview of mixing in 17 chapters contributed by 11 authors. Topics covered include four chapters on aspects of solids and powders mixing, five chapters on multiphase mixing (emulsification, gas dispersion, liquid/solid suspension and multiphase reactions), chapters on mixing low viscosity and high viscosity fluids in turbulent and Iaminar flows, and chapters that focus on mechanical design and specific mixing geometries (static mixers, jet mixing and mechanical aspects of equipment design). I do not know another book on mixing that covers the breadth of material presented here. In the preface the editors note that the present book is the offspring of a short course held over the last 10 years at the University of Bradford (U.K.). This is precisely the feeling one gets reading the book-you’re Iistening in on a “short-course” on mixing. Like a short course, the coverage in the text is descriptive rather than analytical, and provides an overview rather than details. For the most part it is not a “mixing design handbook” with correlations and design criteria, neither is it a research monograph. It occupies a middle ground. I would recommend the book to anyone in the field of mixing who might be a specialist in one area of mixing but would like to get a perspective on other, less familiar, areas of mixing technology. I would also recommend it as an introductory book for those just entering the field of mixing. Nothing is perfect (including this review I am sure) so I will end with some comments on specific strengths and weak-
Photoelectrochemistry, Photocatalysis and Photoreactors. Edited by MARIO SCHIAVELLO. Lectures given at NATO AS1 on Fundamentals and Developments of Photocatalytic and Photoelectrochemical Processes. Reidel, Dordrecht, 1985, 631 pp. This NATO series book, collecting the lectures delivered during the NATO AS1 “Fundamentals and Developments of Photocatalytic and Photoelectrochemical Processes”, held in Erice (Italy) from 20 May to 2 June 1984, is a timely welcome contribution to the general understanding of the subject. Although the field is divided into four broad parts: (a) photoelectrochemistry; (b) homogeneous photocatalysis; (c) heterogeneous photocatalysis and (d) photoreactors, some degree of overlapping in the material disclosed in the lectures is noticeable. It is obvious that some of the new areas require a high degree of interdisciplinary studies and this fact could have only been improved in a book with a few authors. In cases as the one we are dealing with, the situation is almost inevitable. Each part closes with concluding remarks underlying the state-of-the-art achievements, as well as pending problems, prospectives and guidelines for future research. This careful structuring of the edition then allows a rapid evaluation of goals and expectations future researchers should bear in mind. The first part delves mostly into solid state physics and surface physicochemistry, covering such themes as electronic states in ionic solids, semiconductor electrodes and their interaction with light and kinetic aspects of photoelectrochemica1 solar cells, with the interesting addenda of a very opportunely included section on materialengineeringchallenges in the field. This first section is the one which probably better develops the proposed theme with the highest degree of organization. The homogeneous photocatalysis section covers the pre-
3237
nesses. For me the highpoints of the book were the chapters by Nienow (solids suspension), Middleton (gas-liquid dispersion), King (mechanical design), Bourne (mixing and reaction) and Revill (jet mixing). These chapters, by leaders in their respective fields, gave both broad overviews, specific comparisons (for example, a comparison of alternate techniques for gas liquid contacting, p. 325) that are helpful for orienting a novice, ample references (for example, a liberally referenced section by Nienow on factors affecting solids suspensions, p. 303 ff), and illustrative examples (examples of economic considerations by King, p. 274 ff). Unfortunately, the chapter on mixing low viscosity fluids in stirred tanks (Chapter 8), which should be a key chapter on any reference on mixing, was very general, not extensively referenced, and did not give the reader insight into either the fundamental processes involved in mixing, or the effect of mixing variables such as baflle geometry, high efficiency propeller agitators, or multiple impellers. Similarly, in the chapter on laminar mixing (Chapter 12) important references to work by Ottino on mixing kinematics were not referenced so that a reader going to the references in the chapter would miss much of what is new in this area. In summary, I commend the editors for the fine job they have done to assemble this book on mixing. I am sure it will be well received. ROBERT K. PRUD’HOMME Department of Chemical Engineering The Engineering Quadrangle Princeton University. Princeton, NJ 08544, U.S.A.
sent findings related to the fundamental aspects of metal complexes, colloidal semiconductors, electro-transfer and redox systems, simultaneously dealing with basic aspects and new applications (storage of solar energy, the thiosulfate cycle, etc.). A chapter devoted to the analysis of prospectives of photocatalytic and photoelectrochemical processes is also included which will be of great interest for the people working in the area. A considerable part of the concluding remarks, however, is intended to focus on semiconductor particulate devices, which are fully presented in the third part. The depth with which the themes are being treated is equivalent to that of the first part. In the third part, the fundamental aspects of the adsorption and desorption ofgases at solid surfaces is presented, together with a description of heterogeneous photocatalysis and the main reactions that may be conducted in this way. A very important set of recommendations is enclosed at the end of this part: (a) the need to develop methods of making analyses at the liquid-solid interface “in siru” and (b) the need for the development of standard photocatalysts. There is no comparable completeness on photoreaction engineering (4th part) but an effort has been made in outlining the formidable task of developing better photoreactor models capable of taking solid scatterers into account. The contents of this fourth part are made up of lectures with different scopes and deepness of treatment. There is one almost exclusively devoted to the mathematical modelling of the reactor; others which summarize the main applications of thcsc devices at laboratory or commercial scale and others which are circumscribed either to a discussion of the problems appearing in the modelling of these reactors, or to pointing out general aspects on present and future research in this field. Given the state-of-the-art existing at the time the NATO Advanced Study Institute was held, the most outstanding points are clearly mentioned and aiso some of- the more
3238
Book Reviews
relevant future challenges are laid out. Even though the typographic style of the camera-ready reproduced manuscripts is not uniform, the complete edition is carefully presented being a pleasant attraction for the reader. The book as a whole can be regarded as an indispensable introductory reading for those research people trying to enter the field. In short, an opportune, fairly well-organized material, highly recommendable for scientists wishing to make contri-
butions towards the satisfaction of the end-of-the-century energy -. needs. A. E. CASSANO INTEC Casilla de Correo 3OQOSante Fe Argentina
No 91
M.
The book presents a comprehensive overview of mixing in 17 chapters contributed by 11 authors. Topics covered include four chapters on aspects of solids and powders mixing, five chapters on multiphase mixing (emulsification, gas dispersion, liquid/solid suspension and multiphase reactions), chapters on mixing low viscosity and high viscosity fluids in turbulent and Iaminar flows, and chapters that focus on mechanical design and specific mixing geometries (static mixers, jet mixing and mechanical aspects of equipment design). I do not know another book on mixing that covers the breadth of material presented here. In the preface the editors note that the present book is the offspring of a short course held over the last 10 years at the University of Bradford (U.K.). This is precisely the feeling one gets reading the book-you’re Iistening in on a “short-course” on mixing. Like a short course, the coverage in the text is descriptive rather than analytical, and provides an overview rather than details. For the most part it is not a “mixing design handbook” with correlations and design criteria, neither is it a research monograph. It occupies a middle ground. I would recommend the book to anyone in the field of mixing who might be a specialist in one area of mixing but would like to get a perspective on other, less familiar, areas of mixing technology. I would also recommend it as an introductory book for those just entering the field of mixing. Nothing is perfect (including this review I am sure) so I will end with some comments on specific strengths and weak-
Photoelectrochemistry, Photocatalysis and Photoreactors. Edited by MARIO SCHIAVELLO. Lectures given at NATO AS1 on Fundamentals and Developments of Photocatalytic and Photoelectrochemical Processes. Reidel, Dordrecht, 1985, 631 pp. This NATO series book, collecting the lectures delivered during the NATO AS1 “Fundamentals and Developments of Photocatalytic and Photoelectrochemical Processes”, held in Erice (Italy) from 20 May to 2 June 1984, is a timely welcome contribution to the general understanding of the subject. Although the field is divided into four broad parts: (a) photoelectrochemistry; (b) homogeneous photocatalysis; (c) heterogeneous photocatalysis and (d) photoreactors, some degree of overlapping in the material disclosed in the lectures is noticeable. It is obvious that some of the new areas require a high degree of interdisciplinary studies and this fact could have only been improved in a book with a few authors. In cases as the one we are dealing with, the situation is almost inevitable. Each part closes with concluding remarks underlying the state-of-the-art achievements, as well as pending problems, prospectives and guidelines for future research. This careful structuring of the edition then allows a rapid evaluation of goals and expectations future researchers should bear in mind. The first part delves mostly into solid state physics and surface physicochemistry, covering such themes as electronic states in ionic solids, semiconductor electrodes and their interaction with light and kinetic aspects of photoelectrochemica1 solar cells, with the interesting addenda of a very opportunely included section on materialengineeringchallenges in the field. This first section is the one which probably better develops the proposed theme with the highest degree of organization. The homogeneous photocatalysis section covers the pre-
3237
nesses. For me the highpoints of the book were the chapters by Nienow (solids suspension), Middleton (gas-liquid dispersion), King (mechanical design), Bourne (mixing and reaction) and Revill (jet mixing). These chapters, by leaders in their respective fields, gave both broad overviews, specific comparisons (for example, a comparison of alternate techniques for gas liquid contacting, p. 325) that are helpful for orienting a novice, ample references (for example, a liberally referenced section by Nienow on factors affecting solids suspensions, p. 303 ff), and illustrative examples (examples of economic considerations by King, p. 274 ff). Unfortunately, the chapter on mixing low viscosity fluids in stirred tanks (Chapter 8), which should be a key chapter on any reference on mixing, was very general, not extensively referenced, and did not give the reader insight into either the fundamental processes involved in mixing, or the effect of mixing variables such as baflle geometry, high efficiency propeller agitators, or multiple impellers. Similarly, in the chapter on laminar mixing (Chapter 12) important references to work by Ottino on mixing kinematics were not referenced so that a reader going to the references in the chapter would miss much of what is new in this area. In summary, I commend the editors for the fine job they have done to assemble this book on mixing. I am sure it will be well received. ROBERT K. PRUD’HOMME Department of Chemical Engineering The Engineering Quadrangle Princeton University. Princeton, NJ 08544, U.S.A.
sent findings related to the fundamental aspects of metal complexes, colloidal semiconductors, electro-transfer and redox systems, simultaneously dealing with basic aspects and new applications (storage of solar energy, the thiosulfate cycle, etc.). A chapter devoted to the analysis of prospectives of photocatalytic and photoelectrochemical processes is also included which will be of great interest for the people working in the area. A considerable part of the concluding remarks, however, is intended to focus on semiconductor particulate devices, which are fully presented in the third part. The depth with which the themes are being treated is equivalent to that of the first part. In the third part, the fundamental aspects of the adsorption and desorption ofgases at solid surfaces is presented, together with a description of heterogeneous photocatalysis and the main reactions that may be conducted in this way. A very important set of recommendations is enclosed at the end of this part: (a) the need to develop methods of making analyses at the liquid-solid interface “in siru” and (b) the need for the development of standard photocatalysts. There is no comparable completeness on photoreaction engineering (4th part) but an effort has been made in outlining the formidable task of developing better photoreactor models capable of taking solid scatterers into account. The contents of this fourth part are made up of lectures with different scopes and deepness of treatment. There is one almost exclusively devoted to the mathematical modelling of the reactor; others which summarize the main applications of thcsc devices at laboratory or commercial scale and others which are circumscribed either to a discussion of the problems appearing in the modelling of these reactors, or to pointing out general aspects on present and future research in this field. Given the state-of-the-art existing at the time the NATO Advanced Study Institute was held, the most outstanding points are clearly mentioned and aiso some of- the more
3238
Book Reviews
relevant future challenges are laid out. Even though the typographic style of the camera-ready reproduced manuscripts is not uniform, the complete edition is carefully presented being a pleasant attraction for the reader. The book as a whole can be regarded as an indispensable introductory reading for those research people trying to enter the field. In short, an opportune, fairly well-organized material, highly recommendable for scientists wishing to make contri-
butions towards the satisfaction of the end-of-the-century energy -. needs. A. E. CASSANO INTEC Casilla de Correo 3OQOSante Fe Argentina
No 91