Preface

This book has started back in time, during our PhD study in the National Technical University of Athens, School of Chemical Engineering (Greece) when Vassilis was working in the Chemical Reaction Engineering lab and Antonis in the General Chemistry lab both experimentalists, both on natural zeolites but on different subjects: water/wastewater and sewage sludge treatment, respectively. However, it took more than 14 years to for us to mature as scientists and to come up with the ambition and the determination to write a book on Natural Zeolites.

We will never forget our excitement when by accident we have independently discovered a strange behavior of clinoptilolite; the smaller particle size followed slower kinetics towards the ion exchange both in aqueous and solid phase systems, a clear contrast to the basic theory. Our first common article was a reality in 2002: Particle Size Effects on Uptake of Heavy Metals from Sewage Sludge Compost Using Natural Zeolite Clinoptilolite, Journal of Colloid and Interface Science, vol. 250, pp. 1-4.

It is a honor for us to have in our book an impressive number of 36 authors coming from 12 different countries, namely Greece, Cyprus, Romania, Slovakia, Russia, Sweden, UK, Turkey, Iran, Canada, Brazil and Australia. The authors are mainly coming from Universities (61%) and public research institutes (28%) with considerable participation of private sector (11%). Thus, we consider that the geographical, cultural, scientific and professional diversity of the authors guarantees the quality of this work.

The participation of Professor Alan Dyer in our book as signatory of the Preface is an event that we will never forget and will always be an ultimate honor for us.

From this position we have the need to thank by hart all those who have supported us as well as all those who have discourage us throughout our carrier; all experiences are valuable. We have learned that the most important values of life are the ones which are without price; hereby after 14 years we offer you the output of a long-lasting friendship.

For Vassilis and Antonis research is an Art. We hope the readers to appreciate our efforts and to enjoy reading.

Please note that no financial contributions or any potential conflict of interest to any of the book chapters exist.