Preface
xv
of Chapter 7 , where detailed investigation of sorption and diffusion are presented. The
authors showed a good agreement between a theoretical approach based on the NELF
model and the experimental data for mixed matrix membranes. While
the authors of these
chapters introduced nano - particles into high permeability polymer matrices, Chapter 8 by
Suzuki
et al. presents a mixed matrix system based on hyperbranched polyimides. Maybe
there is more reason to introduce nano - particles in such systems, because in polyimides,
it is permeability and not permselectivity that usually requires to be increased. Indeed,
it was shown that permeability coeffi cients of the hybrid membranes increased with
increasing silica content because of additional formation of free volume elements.
Especially large enhancements of CO
2
permeability was
combined with improved CO
2
/
CH
4
separation factor.
Chapter 9 takes a special place in Section II . For some time the problem of acceleration
of membrane permeation of paramagnetic molecules of oxygen mixed with diamagnetic
nitrogen has been discussed in membrane community, but only the team headed by
Grzywna has demonstrated that it is really possible. For this purpose they introduced
neodymium powder into fi lms of ethylcellulose and polyphenyleneoxide and exposed
such fi lms to external magnetic fi elds. Quantitatively, the
observed effects are rather
modest, but the demonstration of the effect itself seems to be the main gain of this really
pioneering study.
The problem of sequestration of carbon dioxide in order to tackle global warming is
of utmost importance for the future of humanity. So, no wonder that several presentations
at ICOM2008 tackled this subject. This is the theme of Section III (Membrane Separation
of CO
2
from Gas Streams); however, to some extent the same problem is discussed in
other chapters of this volume (2, 8, 14, 15). It is well known that Pebax copolymers show
excellent transport parameters in separating gas mixtures containing carbon dioxide.
So, Chapters 12 and 13 deal with certain modifi cations of this material. The
polymers
considered in Chapter 11 are rubbery polydimethylsiloxane and glassy polysulfone and
polyimide Matrimid, but the main emphasis made in this chapter is on the effects
of various minor impurities that can be presented in gaseous feedstock. Chapter 10 con-
siders the application of ionic liquids for the separation of the mixture containing carbon
dioxide. It seems to us that an attentive reader will be able to compare the data of these
four chapters and make some conclusions about advances and drawbacks of various
membranes
for separation of CO
2
.
The last section ‘ Applied Aspects of Membrane Gas Separation ’ contains three chap-
ters. Brunetti
et al. start their contribution with a brief review of membrane materials and
membranes used in gas separation and survey the main directions of industrial applica-
tions of gas separation (hydrogen recovery, air separation, etc.).
In the second part of their
chapter they present a new concept for comparison of membrane and other, more tradi-
tional, methods for gas separation. Their approach includes a consideration of engineer-
ing, economical, environmental and social indicators. Something similar had been written
15 years ago [2] but this analysis is now rather outdated. White (Chapter 15 ) focuses on
a specifi c but very important problem in industrial gas separation:
membrane separation
of natural gas. The main emphasis is on cellulose acetate based membranes that have the
longest history of practical applications. This chapter also contains the results of fi eld
tests of these membranes and considers approaches how to reduce the size and cost of
industrial membrane systems. The fi nal chapter is an example of detailed engineering
xvi
Preface
analysis of another membrane problem – the improvement of performance of a module
for gas dehydration.
Finally, the editors wish to express their gratitude to all the contributors of this book.
We also greatly appreciate the help and understanding of the publishers of this book, John
Wiley
and Sons, Ltd., Chichester, UK.
(1)
Materials Science of Membranes for Gas and Vapor Separation , Yu. Yampolskii , I. Pinnau ,
B. D. Freeman . John Wiley & Sons, Ltd. , Chichester , 2006 .
(2) R. Prasad , R. L. Shaner , K. J. Doshi , Comparison of membranes and other gas separation
technologies , in: Polymeric Gas Separation Membranes , Ed. by D. R. Paul , Yu. P. Yampolskii ,
CRC Press ,
Boca Raton , 1994 , p. 531 .
Benny Freeman
Yuri Yampolskii
